In this edition: The freshest polling about the first debates, the message House Republicans have been sending all year, and the first victims of the campaign cash race.

In my house, the real patriotic holiday is the adoption of the Articles of Confederation, and this is The Trailer.

There won't be a Trailer on July Fourth. Take the day, enjoy your barbecue and/or tank parade, and come back Sunday for all of the latest from Iowa.

We know that the first Democratic debate changed the trajectory of the presidential primary. What we're still trying to figure out is how much it changed the race, and why. For that, The Trailer worked with YouGov Blue and Data for Progress, a liberal advocacy group that has not endorsed any candidate for president. The Post's polling team vetted their research so we could use it here.

The pollsters went into the field before the debate, finding mostly what other pollsters have found, though their sample had an unusually strong level of support for Sen. Elizabeth Warren (D-Mass.). After 1,522 completed voter interviews, focused on registered Democrats who were likely to vote in the primary, pollsters found Joe Biden in the lead, but narrowly.

Joe Biden — 30% 
Elizabeth Warren — 24% 
Bernie Sanders — 16%
Kamala Harris — 7% 
Pete Buttigieg — 7% 
Beto O'Rourke — 3% 
Andrew Yang — 2% 
Cory Booker — 2% 
Amy Klobuchar — 1% 
Jay Inslee — 1% 
John Hickenlooper — 1% 
Julián Castro — 1% 
Tulsi Gabbard — 1%

Even then, before the debate, there was a clear first tier and a less clear muddle beneath it. Only eight candidates were very familiar to the Democratic voters, meaning they had “heard a lot " or “heard a little” about them: Joe Biden, Bernie Sanders, Kamala Harris, Beto O'Rourke, Cory Booker, Elizabeth Warren, Amy Klobuchar, and Pete Buttigieg. Only Warren and Biden had a majority of Democratic voters considering support for them: 57 percent for Warren, 55 percent for Biden.

Biden was dominant, however when voters were asked who would be most likely to defeat President Trump. Overall, 71 percent of voters polled said Biden would “definitely” or “probably” win the election; 56 percent said the same of Sanders, 51 percent said it about Warren, 41 percent about Harris, and 31 percent about Buttigieg.

Then came debate night. Over the next few days, opinion sifted, leaving the same candidates in the front but showing Harris surging and Biden falling into a statistical tie with Warren.

Joe Biden — 23% 
Elizabeth Warren — 22% 
Kamala Harris — 17% 
Bernie Sanders — 15%
Pete Buttigieg — 7% 
Beto O'Rourke — 2% 
Andrew Yang — 2% 
Cory Booker — 2% 
Amy Klobuchar — 1% 
Jay Inslee — 1% 
John Hickenlooper — 1% 
Julián Castro — 1% 
John Delaney — 1%
Tulsi Gabbard — 1%

Behind that movement was a changing voter assessment of who could win the election. Biden moved from 71 to 73 percent on that question; Sanders was basically flat, going from 56 to 55 percent. But Harris surged, with 56 percent of voters saying she could beat Trump, up 15 points. Warren jumped from 51 to 57 percent on the electability question; Buttigieg moved up the same amount, though at 31 to 37 percent he was still far from the front.

But Biden took a little damage on other questions meant to sort out who the “front-runner” is. Before the debate, 59 percent of Democrats said Biden was “most likely” to win the nomination. Warren trailed with 17 percent, and Sanders was at 12 percent; no other Democrat was close. After the debate, 47 percent of Democrats said Biden was likely to be the nominee, 18 percent said the same of Warren, 10 percent said it of Sanders, and 15 percent said it of Harris.

“Warren and Biden are now statistically indistinguishable in the horserace (only one point apart), and the aura of inevitability around Biden has disappeared (less than half of Democratic primary voters now believe he is most likely to win)," Data for Progress's Sean McElwee wrote in an email. “There is no front-runner, only front-runners.”

There is no national Democratic primary. In seven months, Iowa voters will thin out the field; candidates who do better than expected there will get a bounce, as John Kerry did in 2004 and as Barack Obama did in 2008. But the totality of polling since the first debates, heading into the next week of real early-state campaigning, suggests that Biden has indeed softened as a “front-runner” and that three candidates are in a long battle to convince voters they're electable.

Biden's strength remains that Democratic voters basically love him. That's not enough to guarantee a primary victory; even in states where she lost the 2016 primary to Sanders, Hillary Clinton was viewed overwhelmingly favorably by self-identified Democrats. But it's a factor that complicates any quick analysis that compares Biden to Jeb Bush or Rudy Giuliani, early leaders in some primary polls who had shallow party support.

The potential traps for Biden, here and in other polling after the debate, are all related to the strength of other Democrats. The new Quinnipiac poll, which used a smaller national sample than YouGov Blue, found Biden with only a narrow lead among black voters — 31 percent to Harris's 27 percent. A post-debate Univision poll of Latino voters found Biden, who had been viewed the most favorably in that electorate, keeping that positive image. His problem was surges for both Castro and Harris, who emerged to become the candidates viewed most favorably by Latino Democrats. 

There are 28 days left on the calendar before the next round of Democratic debates. In the last period of sustained, in-state campaigning, Warren rose into contention in Iowa, as her favorable ratings among caucus-goers spiked. Tomorrow, Harris, Biden and Sanders will all be in Iowa, the first time since voters got a chance to compare them onstage.

The Data for Progress-YouGov Blue survey was conducted online among a sample of registered voters who said they might participate in their state’s Democratic primary or caucus, including 1,522 respondents before last week’s debates and 1,522 respondents after both debates. Respondents were sampled from the YouGov’s Internet panel members who are matched to the TargetSmart national voter database. This is non-probability survey method since respondents were not selected through a random sample of the population. Respondents were initially selected to match characteristics of the U.S. registered voter population, according to federal surveys and other data sources; results are based on the subset who said they “definitely,” “probably” or “might” vote in their state’s upcoming Democratic primary or caucus.

Scott Clement contributed reporting.

READING LIST

"Democrats convulse over race as debate exchange reverberates,” by Matt Viser and Annie Linskey

How Joe Biden's old votes on busing have complicated the old (by which we mean “one week ago”) racial dynamics of the primary.

“Will Hunter Biden jeopardize his father's campaign?” by Adam Entous

An extraordinarily deep dive into something often chopped up for tabloid consumption.

“Welcome to the 2020 primaries, the era of crowdfunded presidential debates,” by Michelle Ye Hee Lee

How nationalized primary debates have affected fundraising, and how the campaigns try to shape it.

“An unnecessary primary panic?” by Brian Beutler

The case against a June 2019 primary deciding what will be debated in October 2020.

“White House gives tickets to Trump’s July Fourth extravaganza to GOP donors,” by Juliet Eilperin, Dan Lamothe and Josh Dawsey

It's the sort of story that had been truly scandalous for presidents in the past. In 2019, will voters remember it or care?

WHAT I'M WATCHING

If you are not a member of Congress, or don't work for one, you may not have heard of the “motion to recommit.” It's a frequently invoked, rarely successful power available to members of the House of Representatives, one final attempt to alter legislation that is about to come to the floor. With few exceptions, it's used by the minority party to make one last statement about legislation that it is likely to vote against.

The Republican goal this year has been to humiliate swing district members, called “majority makers” by both parties, by asking whether they agree with the new left-wing members from safe seats. In the first six months of the new Congress, Republicans have introduced dozens of “MTRs” and passed three of them. If that doesn't sound like much, consider the context: Only once, during eight years of Republican control of the House under John Boehner and Paul Ryan, did an MTR succeed. That three MTRs have already succeeded has become a major embarrassment for Democrats, starting a fight inside their conference and allowing Republicans to mock the disarray of the majority party.

“The votes speak for themselves,” said Lauren Fine, a spokeswoman for House Minority Whip Steve Scalise (R-La.). “It’s been obvious that there’s a deep divide in their caucus between their radical members and majority makers on how to approach problems like the illegal immigration crisis and growing anti-Semitism as their party marches to the left, away from where the majority of the country is on these issues. We think their constituents should see where they actually stand when it comes time to have to take a vote.”

The MTRs demonstrate the issues that Republicans expect to resonate most in the swing districts in the 2020 election. Three of the 34 MTRs focused on Israel, specifically on the movement to boycott Israeli products unless the country pulls out of settlements occupied by Palestinians. One actually passed, altering a vote to cut off support for Saudi intervention in Yemen by adding “the Combating BDS Act to allow states and local governments divest from entities that boycott Israel.” 

The biggest category of MTRs dealt with immigration — nine of the 34 touched immigration policy in some way or another. One of them passed, adding to a background checks bill language that would alert Immigrations and Customs Enforcement if an undocumented immigrant attempted to buy a firearm. The other eight, which nearly every Democrat opposed, would have added language to a voting rights bill “to support the institution of voting by recognizing that allowing illegal immigrants the right to vote devalues and diminishes the voting power of American citizens”; cut funding for the Census “to fund up to 100 new immigration judge teams”; and given the federal government power “to allow the use of federal and state gang databases to deny green card eligibility to any individual who is a known member of a criminal gang.”

Most of the other immigration-focused MTRs were attempts to add emergency border security funding to spending bills; each vote against them was tucked away for future campaign ads. Last year, the late focus on a caravan of migrants working its way toward the U.S.-Mexico border did little or nothing to rescue Republicans from the wave against their House candidates. But the only actions they've been able to take in the House tell us that 2020 is going to be about immigration again.

POLL WATCH

Iowa Democratic caucuses (Suffolk, 500 likely caucusgoers)

Biden — 24%
Kamala Harris — 16%
Elizabeth Warren — 13%
Bernie Sanders — 9%
Pete Buttigieg — 6%
Amy Klobuchar — 2%
Cory Booker — 2%
Tulsi Gabbard — 1%
Michael Bennet — 1%
Julián Castro — 1%
John Delaney — 1%
Beto O'Rourke — 1%
Andrew Yang — 1%

This is Suffolk's first report on the field in Iowa, so there are no trendlines to compare it to. But it's the latest in a series of early-state polls that show the vast majority of Democrats shopping for a candidate who isn't Joe Biden or Bernie Sanders. That's been brewing all year; the first Des Moines Register Iowa Polls found that three in 10 Democrats viewed Joe Biden as too old to be president and four in 10 saying the same of Sanders. As the universe of potential candidates becomes clearer, Democrats are experimenting with what's new.

The crosstabs suggest that the experimentation is mostly helping two female candidates. Harris and Warren are the most popular second choices of Iowa Democrats; Biden and Sanders have slipped on that question. Among both Democrats and the broader electorate, Warren and Harris have grown more personally popular, with higher favorable ratings than Sanders, who has spent two weeks arguing that he's the most electable candidate in the field. (State polling has consistently shown Sanders ahead of Trump, though Biden and Warren have led in the same surveys.)

Who has the best chance to defeat Donald Trump? (Quinnipiac, 554 Democratic voters)

Joe Biden — 42% (-14)
Kamala Harris — 14% ( 12)
Bernie Sanders — 13% ( 1)
Elizabeth Warren — 9% ( 6)
Pete Buttigieg — 1% (-3)
Cory Booker — 1% (-2)
Tulsi Gabbard — 1% ( 0)

The trendlines, in parentheses, are from the end of April. In two months, and after one debate, Biden remains the Democrat who the party's voters see as most likely to win in 2020. But the debate took a chunk out of him; for the first time since that question has been asked, Biden has a plurality, not a majority, on the electability question. The thorny “who can win” question is all about external inputs, and so long as national polls and state polls show Biden running stronger than the field, the premise of his candidacy is strong. If that changes, a number of Biden rivals stand to benefit. The Bernie Sanders “electability” push, best seen in new bumper stickers that say “Bernie beats Trump,” is predicated on Biden looking less electable and voters seeking a safe harbor. What every other campaign wants: polling that shows them running stronger in the Midwest than Biden.

Health care (CNN, 1,613 voters)

Should the government provide a national health care plan, even if it requires higher taxes?

Yes — 56%
No — 40%

Should a national health care plan replace all private insurance?

No — 57%
Yes — 37%

Should government-sponsored insurance be available to undocumented immigrants?

No — 59%
Yes — 38%

The left has largely won the public debate about health insurance since 2016, with a few gigantic caveats. After a decade of being told that “government-run insurance” would result from any Democratic victory, voters are generally warm to the idea of a national universal insurance plan. But most Democrats leading in the primary have endorsed one simple and unpopular idea (undocumented immigrants being eligible for federal benefits) and one complicated but unpopular idea (phasing out private insurance, something that Medicare-for-all would do to basic plans, but not supplementary plans).

MONEY WATCH

Republicans. We have a record for presidential incumbent fundraising: President Trump raised $54 million for his own reelection and $51 million for the Republican National Committee. That shatters the bar set by President Barack Obama eight years ago, when he raised a combined $86 million for reelection. Obama was frequently criticized, even by his own party, for holding so many fundraisers; Trump, who self-funded the early stages of his 2016 campaign, takes no such heat. But Trump has also bested the last Democratic campaigns when it comes to small-dollar donors.

Democrats. It may not last long, but Pete Buttigieg is the party's new fundraising leader; he collected $24.8 million for his campaign, combining small dollars with a throwback embrace of big donors and fundraisers. That put him ahead of Bernie Sanders, who raised $18 million, down incrementally from the $18.2 million he raised in the first quarter. Sanders's haul was more than enough to run a campaign on, and was bolstered by a $6 million transfer from the his Senate fund, but it showed a campaign that was struggling for momentum, even as it got more small donors; 99.9 percent of those who donated, per the campaign, could give again without hitting the limit. This, according to the Sanders campaign, was the only way to win.

“When you go into those high-dollar donor meetings, their support comes with a cost,” Sanders campaign manager Faiz Shakir said on a call with reporters.

At the same time, John Hickenlooper's campaign was losing some key early staff amid reports that he would raise around $1 million in the second quarter.

IN THE STATES

Colorado. Two of the Democrats in the crowded U.S. Senate primary raised more than $1 million in their second quarters, the latest evidence of a crowded and competitive race for the party's most attractive opportunity to go on offense. Former state senator Mike Johnson raised $1.6 million; former diplomat Dan Baer raised $1.4 million. Both of them put up more than John Hickenlooper is expected to announce raising in the second quarter. Something to watch: While John Hickenlooper struggles to raise money for his presidential bid, the Democratic campaigns in Colorado are signaling that he would not clear the field if he was enticed to come back and run for Senate.

Maine. Sara Gideon, the state legislative leader who last week announced her campaign against Sen. Susan Collins, announced that she'd raised $1 million. At least 2,000 donations, per the campaign, came from Maine; the wild national interest from liberals who want to beat Collins helped put up the rest. Gideon has a primary in front of her, with liberal activist Betsy Sweet declaring her candidacy a few days earlier; Sweet's fundraising is not yet known.

South Carolina. Jaime Harrison, the former state Democratic chairman who made friends in the party with a 2017 DNC chair run, raised $1.5 million in his first quarter as a candidate. That helped him clear a low bar: No Democrat has raised as much in a race against an incumbent Republican senator. (South Carolina has had two Republican senators since 2005.)

2020

Cory Booker. He joined the debate over immigration policy with a plan to close private prisons and immigrant detention centers.

Joe Biden. He's returning to Iowa on Wednesday for his third campaign swing through the state; he lost an early fundraising “bundler” since the first debates but is on track to replace him; he also won his second gubernatorial endorsement, from Connecticut's Ned Lamont.

Kamala Harris. She heads to Iowa on Wednesday and Thursday and will campaign in heavily black parts of South Carolina over the weekend, after some concerns that Democrats were not paying attention to that part of the state.

Elizabeth Warren. She's spending Tuesday and Wednesday in Nevada before heading back toward Houston for the National Education Association's meeting; and after that, the Essence Festival in New Orleans.

Amy Klobuchar. She's in New Hampshire for most of the July Fourth week, holding a series of public events and house parties.

Steve Bullock. He's in Iowa for July Fourth, stopping at four parades; he's also sending his first piece of direct mail.

John Hickenlooper. He hired a new campaign manager, M.E. Smith, fresh from Sen. Bob Casey of Pennsylvania's reelection; he will return to Iowa on Sunday and Monday.

John Delaney. He held his 100th public event in New Hampshire on Tuesday, part of a three-day swing that keeps him in the state on July Fourth.

Eric Swalwell. He's spending the middle of the week, and the holiday, in New Hampshire.

Joe Sestak. He's holding another event in Iowa, where he's spent all of his time so far, on Thursday: a climate-focused roundtable.

COUNTDOWN

. . . three days until some 2020 Democrats talk to the National Education Association in Houston
. . . nine days until some 2020 Democrats talk to the League of United Latin American Citizens in Milwaukee
. . . 10 days until some 2020 Democrats talk to the Essence Festival in New Orleans
. . . 11 days until some 2020 Democrats talk to Netroots Nation in Philadelphia