In this edition: Why you can't see negative ads in Iowa, why Democratic voters aren't focused on impeachment, and what the senators trapped in Washington are doing with their time.

If you think it's easy to stay awake for 12 hours drinking only milk, you should be a senator, and this is The Trailer.

The on-again, off-again fight between Sen. Bernie Sanders and former vice president Joe Biden lasted for days, yet neither candidate looked particularly happy to wage it. By Monday night, Sanders (I-Vt.) had stopped referring to Biden's old willingness to “adjust” Social Security and apologized for a surrogate calling Biden “corrupt.” By Wednesday morning, Biden was scoffing at a reporter for asking why his campaign ran a short web video defending himself against Sanders on Social Security.

“Why, why, why, why, why, why, why?” Biden told CBS News's Ed O'Keefe, making fun of the question. “He apologized for saying that I was corrupt. He didn’t mention anything about whether or not I was telling the truth about Social Security.”

Locked in a tight race for the Democratic nomination, the leading candidates have only tentatively gone after each other. What's more striking is that, less than two weeks before Iowa voters begin to winnow down the field, no leading Democrat has run a traditional ad — no TV, no mail — attacking one of their rivals. A year of arguments about electability, single-payer health care and everything else has not resulted in anyone going truly negative. 

That's unusual, especially at this point in a campaign. But it reflects the nervousness Democrats felt after 2016, when they asked whether the long and bitter tone of that year's primary weakened Hillary Clinton in the general election. And it grows out of a shared worry that candidates who grapple with each other will simply open a path for someone else, as they remember a hyper-negative Dick Gephardt doing when he went after Howard Dean, 16 years ago.

“Taking a sledgehammer to the other guy isn't productive in a multicandidate race,” said Mark Longabaugh, who cut ads for Sanders's 2016 campaign and now works for Andrew Yang. “The last primary became a bipolar race, and in that situation, you can be more critical of your opponent. When a voter peels off them, you're their only option. That's not where we are now.”

This year, the campaigns are so wary of going negative that they'd rather accuse rivals of shooting first. When Biden's campaign released its web video Tuesday, Sanders's campaign manager, Faiz Shakir, said that he'd “just released the first negative ad of the 2020 Democratic primary.”

The remaining Democratic candidates have criticized one another, sometimes when prompted and sometimes as part of a plan. But they've kept it to interviews and debates, never letting it spill into paid advertising. 

When the Sanders campaign purchased PetesWineCave.com to draw attention to a luxurious fundraiser for former South Bend, Ind., mayor Pete Buttigieg, it alerted reporters and supporters around the December debate, then never talked about it again. When Sen. Elizabeth Warren (D-Mass.) bristled at Biden's attack on Medicare-for-all, she said the plan's critics were running in “the wrong primary.” She never uttered that phrase again, while Biden spent more than a week looking for blowback, telling voters that Warren had revealed an “elitist attitude” about policy.

None of this would have made a splash in the past few primaries, especially the ones fought by Republicans. In the final days before the 2008 Iowa caucuses, Mitt Romney ran ads attacking Mike Huckabee as “soft on government spending” with a “ludicrous” foreign policy, while running ads in New Hampshire that accused John McCain of voting “to allow illegals to collect Social Security.”

Romney recycled those tactics four years later, successfully, tearing the bark off every opponent who threatened him in a primary state. When Newt Gingrich rose in the polls, Romney directed voters to a NewtFacts website where they could learn that he supported “amnesty for millions of illegal immigrants.” When Rick Santorum emerged as a threat, a pro-Romney super PAC attacked the former U.S. senator from Pennsylvania for hiking federal spending. And in 2016, some of Romney's allies resurfaced in an anti-Trump super PAC, which blistered him in Iowa.

There are vocal Democrats who worry that a Sanders nomination, or a win for Warren, would be a disaster. But none of them has elbowed into this race beyond columns or TV appearances. Neither have conservatives. The Club for Growth, which had intervened in the 2004 primary to hurt Dean, ran two ads in 2019, one against the flamed out candidacy of former congressman Beto O'Rourke, portraying him as a privileged nonentity, and one against Biden, amplifying Sen. Kamala D. Harris's criticism of Biden's work with segregationists.

This made no calculable impact on Democratic voters. Neither did a series of Trump campaign spots against Biden, which the campaign jujitsu'd into an argument for Biden's electability; Republicans were attacking him because they were nervous. And Democrats repeatedly refused to criticize Biden, from Warren declining to say whether her ethics plan would prevent a vice president's son from working for a foreign company to Sanders apologizing hours after Zephyr Teachout, a new supporter and longtime ally, called Biden corrupt. At one point, Warren even attacked Facebook for refusing to remove an anti-Biden spot.

Democrats had a much calmer 2016 primary than Republicans did, though they often remember it differently. Only one negative ad was run in Iowa, by a super PAC designed to help former Maryland governor Martin O'Malley by attacking Sanders's record on guns. On air, Sanders's own negativity was subtle; an ad that referred to some unnamed candidates who “say it’s O.K. to take millions from big banks and then tell them what to do.” Clinton's campaign punched back, saying that Sanders had broken a pledge not to run negative ads. 

But it did not respond with its own on-air attack, and Sanders's campaign had previously opted not to attack Clinton over the investigation of the private email server she had used while secretary of state, a story that engulfed her campaign.

“I remember taking flack for taking emails off the table, but it was the right thing to do for a variety of reasons,” said Longabaugh. “Hillary had just come off the hearings over Benghazi. The Democratic electorate was outraged at the behavior of Republicans. There was no upside.”

This year, the harshest Democratic attacks have been contrast ads, largely focused on Medicare-for-all. The Sanders and Warren campaigns saw Buttigieg's summer ad campaign for “Medicare for all who want it” as an attack, crafted to avoid the impression that the well-liked candidate would go negative. One spot quoted critics of Medicare-for-all, who warned about people with employer-provided insurance being forced into new plans.

But that was it, and those ads have disappeared in the final stretch. Even super PACs, the vectors for most attack spots in the past few cycles, have been muted; just Biden benefits from one, and Unite the Country swore from the outset that it would not attack fellow Democrats. Its latest spot, which shows footage of a stormy sea to represent how a Biden presidency would calm things down, could just as easily be selling blood thinner as selling a candidate.

Real attack ads, the ones making candidates' worst qualities infamous, just aren't appearing anywhere. The Sanders-Biden fight showed one reason, with the videos making each argument — that Sanders was attacking dishonestly and that Biden was covering up his record — entirely on Twitter, with no ad buy aimed at voters. 

Those past campaigns hinted at the other reasons. Nervousness about the general election is embedded in most of what Democrats do, and they fret about making attacks that could backfire and help President Trump's campaign. In 2008, when Hillary Clinton and Barack Obama were competing in South Carolina, Obama ran a radio spot that accused Clinton of lying about him.

“She'll say anything and change nothing,” a narrator warned. 

Eight years later, that ad was rediscovered and repurposed by Trump.

READING LIST

"Biden says he refuses to be part of impeachment witness deal," by Matt Viser

The ongoing effort to drag the Democrat into the president's trials.

"Does Tom Steyer have real momentum or just a ton of money?" by Evan Halper

On the campaign bus with a candidate doing better than people expected in South Carolina.

"What Pete Buttigieg learned organizing for Obama in Iowa: ‘You can reach people.’ And wear boots," by Holly Bailey

The lessons of skinny kids with funny names.

"The elite media's Amy Klobuchar blind spot," by Libby Watson

Should a candidate struggling to break out of fifth place get such glowing coverage?

"Black lawmakers’ presidential endorsements are the most spread-out they’ve been in recent history," by Eugene Scott

The party isn't deciding.

"Bernie Sanders's rise means more talk about electability than revolution," by Emma Kinery

A changing focus for a candidate who voters sometimes can't believe is competitive in the polls.

IMPEACHMENT WATCH

The latest on the impeachment of President Trump

ON THE TRAIL

AMES, Iowa — On Tuesday, with the Senate's impeachment trial finally underway, Joe Biden walked into a conference center on Iowa State University's campus and began talking about President Trump.

Impeachment didn't come up at all.

Instead, the former vice president dealt briefly with how he'd been the "object of affection" for Republicans for a while and how "Trump has spent over 12 [million] to 15 million bucks so far in negative ads that mainstream stations won't even play, because they know they're just lies." The point, which Biden often makes, was not even that Trump would be forced from office but that a "healer" would need to replace him.

The impeachment of Trump, which has led to only the third trial of a president in American history, has captivated Washington and pulled a third of the remaining Democratic candidates briefly off the trail. 

But in Iowa, it's not driving conversations. The days of Democrats imagining "the end stages of the Trump presidency" or some revelation emerging that would shame him out of office ended long ago. The "Mueller Time" T-shirts and boxes of ImpeachMints are packed away with the Christmas decorations. Voters do not expect Trump to be pulled out of office, and some of them have largely tuned out news about him, period.

"Trump is just a symptom of problems that go much deeper," said Faye Doney, 30, a supporter of Andrew Yang's candidacy who had come to hear out Biden. "I have open ears, and open eyes, and people's problems are more important to me than whatever's on the news. My sister's working 10-hour days trying to support kids through a divorce. Politics are the last thing on her mind."

Some voters were paying attention. Dave Brighton, the 61-year-old manager of a Cedar Rapids dry cleaning company, said before a town hall there with former South Bend, Ind., mayor Pete Buttigieg that he watched coverage on MSNBC "every day," but not with the expectation of Trump's removal from office.

"I just want to see basically what's happening," he explained. "I know he's probably not going to be [removed]. I know the Republicans are going to block it. I just want to see the defense that Democrats are putting up and how hard they're going to fight."

Impeachment's disappearance from the Democratic mind happened quietly and slowly. Just six months ago, a questioner could still thicken the air in a town hall by asking a candidate if they supported Trump's impeachment. Democratic strategists, who had internalized the idea that Republicans were hurt by the 1998 impeachment of former president Bill Clinton, worried about discussing it. Sen. Elizabeth Warren (D-Mass.) benefited, on the margins, from being the only Democrat who said that former special counsel Robert S. Mueller III's report made the case for Trump's impeachment. But no candidate suffered from punting on impeachment questions.

Since then, impeachment had become noise — dramatic and historic but not relevant to the choice in Iowa. In interviews, many voters continued to say "impeachment" when they meant "removal," predicting that Trump would not be "impeached." The word had so much power, for so long, before Democrats got a real-life example of how a president cannot be removed from office if at least 34 senators don't want him to be.

Karen Welter, 75, said that she was following the impeachment through local news and TV and that she had watched "some" of the hearings Tuesday, finding Rep. Adam B. Schiff (D-Calif.) to be "impressive," while understanding that Trump would remain in office.

"It's amazing to me that he can be so far out," Welter said. "I guess that's why I still listen to him. I keep following him because I can't believe he lies so much and his followers still follow him."

Biden and Buttigieg, the two strongest-polling candidates in Iowa who are not tied up by the trial itself, never get into its details. Instead, they describe generally how the president makes their audience, Democratic voters, so nervous, embarrassed and stressed. 

"Imagine the first time that the sun comes up over Cedar Rapids on a day when Donald Trump is no longer the president," Buttigieg said in Cedar Rapids, repeating a theme of his speeches since before the House's impeachment debate began. "Just to put the chaos behind us, to put the corruption behind us. To put the tweets behind us. Wouldn't it be nice?"

Mike King, 59, said he watches coverage of Trump "when I have the stomach for it" and has tuned in to "a little bit" of impeachment coverage.

"It doesn't seem like it's a cliffhanger," King said. "It seems pretty obvious that there's bad stuff going on. From the day he was elected, you knew he was going to do something stupid."

AD WATCH

Amy Klobuchar, "Buckle Up." A two-fer, this spot leads with Sen. Klobuchar's Quad-City Times endorsement while telling voters about her big executive action agenda by saying she doesn't even have time to share it in an ad. It cuts off, on purpose, by the time she gets to "anti-trust enforcement, affordable housing!" The ad borrows a little inspiration from an ad that former senator Paul Wellstone ran in 1990, in which he warned that he'd "have to talk fast" and go through his entire biography and agenda because he didn't have a lot of campaign money.

Bernie Sanders, "Transform This Country." The senator continues to capitalize on the speech and rally he held in New York after recuperating from a heart attack, where he reframed the goal of his campaign: a country where you will "fight for someone you don't know." That message has not been countered effectively by more moderate candidates.

Mike Bloomberg, "Pentagon." The former mayor continues to pitch himself as a sensible leader who would end the erratic Trump presidency, focusing this time on whether the president can lead the military without blundering into disasters and ignoring expert advice. "Arrogance. Ignorance. Chaos. Enough."

POLL WATCH

New Hampshire primary (WBUR, 426 likely voters)

Bernie Sanders: 29% ( 14)
Pete Buttigieg: 17% (-1)
Joe Biden: 14% (-3)
Elizabeth Warren: 13% ( 1)
Amy Klobuchar: 6% ( 1)
Tulsi Gabbard: 5% (-)
Andrew Yang: 5% (-)
Tom Steyer: 2% (-1)
Deval Patrick: 1% ( 1)

No Democratic candidate, not even Sanders, is on track to repeat the 60 percent rout he won in 2016. But this is the first New Hampshire poll we've seen in a while that finds any candidate significantly ahead, instead of bunched together in a top four. That could mean we're looking at an outlier, but one trendline stands out: Sanders has recovered the sky-high favorable ratings that slipped a bit over 2019. Likely voters now view him favorably by a 56-point margin, well ahead of the other "top tier" candidates; Buttigieg gets a 41-point margin, Warren gets 31 points, and Biden gets 25. Every candidate's favorable numbers have actually grown since the last poll, in November, with Andrew Yang (now with a 44-point positive rating) moving up the most.

Should the primary system be changed? (Monmouth, 372 Democratic voters)

Create a national primary: 58%
More states vote on same day as Iowa/New Hampshire: 15%
Keep the current system: 11%
Create grouped primaries: 10%

This newsletter avoids head-to-head national primary polls for the simple reason that there is no national primary, no one day when voters get to pick a nominee. That usually renders 49 or 48 states irrelevant in a crucial part of the process, as the contenders get winnowed down to two or three options. Surprise, surprise, most Democratic voters are tired of it: Monmouth finds a clear majority of them preferring some sort of national primary, after previous polls found even Iowa and New Hampshire voters with mixed feelings about their status. 

CANDIDATE TRACKER

The four senators who've paused campaigning while sitting for the impeachment trial have been approaching the problem in different ways. Amy Klobuchar, by far, has done the most TV, from live cable hits to packages that ran for voters in Iowa. Elizabeth Warren sat for an interview with MSNBC's Rachel Maddow. Bernie Sanders and Michael F. Bennet have done marginally less TV, with Sanders telling reporters this week that he was balancing his duties "with much difficulty," with no pretense that he was enjoying it.

"We have a great group of volunteers in Iowa, New Hampshire knocking on doors in very, very cold weather, and we’re gonna be dependent on them," said Sanders. "I have to do my constitutional responsibility and I’m here."

All four senators will return to the trail as soon as able, which is looking like Saturday night. Warren, Sanders and Klobuchar will zip to Iowa, while Bennet, who has largely given up on the first caucus state, has events scheduled in New Hampshire.

Joe Biden. He picked up more endorsements from members of Congress, pushing his total number of supporters from the Congressional Black Caucus to 15.

Pete Buttigieg. He's returning to Iowa on Saturday for more town halls, after trips to New Hampshire and South Carolina and a fundraiser in Illinois.

Tulsi Gabbard. She filed a lawsuit in New York against Hillary Clinton, claiming that the 2016 nominee's comment that Gabbard was being "groomed" as a third-party spoiler candidate cost the Hawaii congresswoman $50 million. Meanwhile, Gabbard is continuing to campaign in New Hampshire.

Mike Bloomberg. He added more support from friendly mayors, with an endorsement from San Francisco's London Breed, who took office long after Bloomberg's tenure in New York was over. On Wednesday, in a speech to the United States Conference of Mayors, Bloomberg endorsed statehood for the District of Columbia; the district's mayor, Muriel Bowser, remains neutral on the primary.

Andrew Yang. He picked up the support of Marianne Williamson, who quit the presidential race this month after failing to get traction in early states. In a series of Instagram posts, Williamson explained that "Bernie and Elizabeth will make it past Iowa and beyond," but Yang needed a boost: "I’m lending my support to Andrew in Iowa, hopefully to help him get past the early primaries & remind us not to take ourselves too seriously." In 2016, Williamson endorsed Sanders for president. Yang is continuing to campaign in Iowa through the caucuses.

COUNTDOWN

... five days until the special legislative election in Texas
... 11 days until the Iowa caucuses
... 19 days until the New Hampshire primary
... 30 days until the Nevada caucuses
... 40 days until the South Carolina primary
... 41 days until Super Tuesday