In this edition: Democrats tilt away from super PACs, the primary challenges gear up ahead of 2020, courts firm up Maine's new election system and Tom Steyer finds an actual use for LinkedIn.

For the first time, the War Powers Act has been used by the Senate to rebuke a foreign intervention carried out by the executive branch. This is The Trailer.

Political donors are celebrating a big anniversary this week. Four years ago, Jeb Bush announced he was exploring a potential presidential candidacy by creating Right to Rise, a super PAC that could raise unlimited sums of money.

Once Bush became an official candidate, he would be unable to raise money for the PAC; post-Citizens United campaign finance laws would prevent him from coordinating with the PAC at all. And so, for six months, Bush helped the PAC raise money, piling up $103 million before he said the magic words that made him a candidate. 

"You might as well front-load it if you can," Bush told The Washington Post in 2015.

We know the ending/punchline: Bush quit the race after disastrous showings in the first three contests. In the long run, Right to Rise's failure might have the same impact on presidential campaign financing as Barack Obama's 2008 decision to abandon the public campaign finance system and maximize small dollar donations. More than 30 Democrats are considering campaigns for president, but few are talking about launching super PACs, and some are ruling it out.

The latest Democrat to nix the super PAC idea is Julián Castro, the former secretary of Housing and Urban Development who launched an exploratory committee on Wednesday. Castro's stated plan was to tour the country for one month and make an announcement about the presidency on Jan. 12. In theory, that would let him shake the money tree just as Bush did four years ago, but a spokesman for Castro said he had no intention of seeding a super PAC.

"Secretary Castro will not take PAC donations to his committee, and discourages the creation of a super PAC to support his candidacy," said Jennifer Fiore, an adviser for the not-quite-candidate.

Most of the candidates seriously looking at 2020 have made similar noise about super PACs. Sen. Bernie Sanders (I-Vt.) — whose lack of a super PAC was one of his steadiest 2016 applause lines — has no plan to endorse one for 2020. (Granted, Sanders benefited from a separate super PAC financed by a nurses' union in 2016 and could do so again.) In his most recent memoir, Joe Biden wrote that he would have sworn off a super PAC had he run in 2016: "I knew there was big money out there for me, but I also knew people were sick of it all.”

Other candidates looking to claim the left-wing lane of any 2020 primary, like Sens Elizabeth Warren (D-Mass.), Kamala Harris (D-Calif.), and Kirsten Gillibrand (D-N.Y.), have suggested they would reject super PACs. As Hillary Clinton's 2016 campaign manager Robby Mook told the New York Times this week, the lasting dynamics of that race left super PACS "a liability as much a strength."

The downside of a super PAC has only grown since then; to have one is to invite accusations of being bought and paid for by the rich. In 2016, Donald Trump found the accusation also had power in a Republican primary. No less than eight super PACs were created to boost the campaign of Sen. Ted Cruz (R-Tex.), and Trump's campaign mocked the senator relentlessly for it; Hope Hicks, Trump's spokeswoman at the time, accused Cruz of "financial corruption of the highest order." The impression that Trump was funding his own campaign, which stopped being true months before the general election, proved immensely helpful for him.

If few Democrats endorse super PACs for 2020, it could change what we think about their enormous field of candidates. Since the birth of the "super PAC" in 2010, candidates who struggled to raise grass-roots money have been able to stay afloat. In 2012, when Rick Santorum's campaign foundered financially, the Red, White, and Blue Fund largely bankrolled by Foster Friess provided air cover for months. In 2016, Bush was just one of several candidates whose campaign raised less money than his affiliated super PAC; Chris Christie and Sen. Marco Rubio (R-Fla.) stayed in the race through weak periods thanks to a flow of big money, and both took in less money for their own campaigns than the super PACs did on their behalf.

Many 2020 Democrats are preemptively declining that arrangement, and with it, a kind of campaign life raft. That will not stop independent groups from launching draft campaigns or unofficial super PACs, as happened in 2018 with a pop-up for Rep. Beto O'Rourke (D-Tex.), created by the Democrats' Senate super PAC. In the 2020 general elections, Democrats expect the party's key super PACs, like Priorities USA, will stay active; the argument now is simply over disarming in the primaries.

Not every candidate will follow in Castro's steps. Rep. John Delaney (D-Md.), the first announced Democratic presidential candidate, said in an email that he skipped the exploratory stage because "exploratory committees don’t serve much of a point," but noted that supporters had launched “The Right Answer PAC," a super PAC, to help him. Rep. Eric Swalwell (D-Calif.), who is traveling to New Hampshire and Iowa in the coming days, said in an interview that he would suggest that any independent PAC that supported him be completely transparent about its donors. But so long as super PACs were legal, he said, he would not preemptively denounce one on his behalf.

"I want to get rid of those," said Swalwell, referring to super PACs, "but I also don't want to fight with one hand behind my back."

DEMS IN DISARRAY

On Wednesday, Republicans nearly capsized the farm bill after adding language that prevented House critics of the U.S. intervention in Yemen from using the War Powers Act to stop it. (On Thursday, the Senate voted 56 to 41 to cut off support for the military intervention, a rebuke to the president he is expected to ignore.)

It's a common technique in the House: An unpopular measure is snuck into something that must pass. The gimmick worked, but only because five Democrats who had worked on the farm bill broke with their party to support it.

In the new Democratic Party, that meant that five more Democrats were being talked about as targets for primary challenges. Alexandra Rojas, whose group Justice Democrats is recruiting challengers in 2020 House races, said the farm bill vote had galvanized activists who were on the verge of winning the Yemen fight.

"Five Democrats, many of whom rake campaign donations from arms manufacturers and the defense industry, voted with the party of Donald Trump instead of fighting for peace and ending the killing and starvation of tens of thousands of children in Yemen," said Rojas. "It’s disgraceful for these Democrats to sell out their voters especially when progressive leaders led the charge on this and even got 17 Republicans to cross over to join them."

Other activists set to work making the five Democrats famous. Sean McElwee, the co-founder of Data for Progress and a leading voice for primary challenges in safe Democratic seats, pointed out that Rep. C.A. Dutch Ruppersberger's (D-Md.) district is safely blue, 11 points more Democratic than the country at large. Reps Al Lawson (D-Fla.) and David Scott (D-Ga.) represent even bluer districts, and Lawson fended off a primary challenge just four months ago; there is now talk of finding primary challengers to both men.

Reps Jim Costa (D-Calif.) and Collin Peterson (D-Minn.) are being approached differently. Costa, a leader of the conservative Blue Dog caucus, represents a California seat that has gotten bluer, but the state's top-two primary system has, ironically, made it harder for liberal challenges to break through.

Peterson, who represents the reddest seat of any House Democrat, has never been a target for challengers because some advocates, like McElwee, see the left's best opportunities in districts that lean left already. But Peterson was the only "aye" voter who talked to The Washington Post on Wednesday; his admission that he didn't "know a damn thing" about the Yemen policy made him infamous within hours.

Wednesday's vote was the biggest jolt of the month for the pro-primary movement, which has been expanding its target list. The most concrete evidence of a 2020 primary challenge has come in Massachusetts, where a number of ambitious Democrats are now talking openly about trying to defeat Rep. Seth Moulton (D-Mass.) over his long and unsuccessful push to oust Nancy Pelosi as the party's leader. At least one Democrat has also reached out to insurgent groups about challenging Rep. Kathleen Rice (D-N.Y.), another one of Pelosi's most persistent critics.

AD WATCH

Immigration. People for the American Way is running extremely early 2020 digital campaign ads, aimed at non-white voters, which consist almost entirely of images that show child migrants being repelled from the border. "These are shameless Trump and Republican policies," it warns.

2020

Bernie Sanders. He met privately with Elizabeth Warren on Wednesday night; there is constant and easy debate, on the left, about whether the movement's vote would be split if both ran for president.

Tom Steyer. He's continuing his five-issue speaking tour tonight with a town hall in Fresno, Calif; he is also, as Ruby Cramer first noticed, advertising on LinkedIn for a potential presidential bid.

Eric Swalwell. The California congressman will be in New Hampshire on Friday, then Iowa six days later, for a trip that will include a town hall with Parkland survivor Cameron Kasky.

Marianne Williamson. The self-help author went on the Young Turks to discuss her campaign's hope of dismantling the "authoritarian corporatism" that she said runs the country.

Elizabeth Warren. On Friday, she'll deliver a commencement address at Maryland's historically black Morgan State University.

WHAT I'M WATCHING

Maine justice. Whatever slim hope that Rep. Bruce Poliquin (R-Maine) had of staying in Congress probably died on Thursday, after Judge Lance Walker denied the congressman's request to throw out the results of the state's first instant runoff election. Walker, a Trump appointee, pulverized the arguments that Poliquin's team made, starting with one about how voters might have been confused by a system that allows them to rank candidates in the order of who they most and least want to see elected.

"The RCV system implemented in Maine is not so opaque and bewildering that it deprives a class of citizens of the fundamental right to vote," Walker wrote. "I find the form of the ballot and the associated instructions more than adequate to apprise the voter of how to express preferences among the candidates."

Walker also dismissed the only expert testimony Poliquin produced in court — an argument from a political scientist that in an election with more than two candidates, voters might not realize which candidates are most likely to come in first and second place.

"In addition to being cynical, these conclusions are not grounded in anything approaching a reliable standard that may be informative of the constitutional questions," Walker wrote. "They are instead provocative reactions to a new system of selecting representatives to Congress, and such reactions often are the byproduct of change."

Finally, Walker challenged the idea, advanced by Poliquin and Republicans, that some voters in Maine's massive 2nd District were disadvantaged because of a system that allowed voters to pick second or third choices.

"A majority of Maine’s voters have expressed their interest in a manner of election that gives voice to these varied perspectives, while also permitting representation by those candidates most voters regard as the best of the practical alternatives," Walker wrote. "Through RCV, as applied to the Second District house race, majority rights have been advanced, and no minority rights have been burdened unduly, if at all."

Poliquin's chances of scrapping the election results have probably vanished. All that's left is a recount, which the congressman must pay for (and could pay for from campaign funds) if it does not put him ahead of Democrat Jared Golden; then, an official certification of the election, which would be up to Democratic Gov.-elect Janet Mills when she takes office on Jan. 2.

READING LIST

"‘My 5-year-old could probably sort this out,’ Yoder says of border wall standoff," by Bryan Lowry and Lindsay Wise

Given that the border wall fight will define the next two weeks — and could restart in a different form once Democrats control the House — this is a bracing look at how the Republican with committee jurisdiction over the wall funding has been boxed out.

"A most unpredictable road to the 2020 Democratic nomination," by Amy Walter

A nice distillation of what the smart people expect to change in the run-up to Iowa. The big question, which seemed easier to answer a few months ago, is how much power the president will have to define what Democrats are talking about.

"North Carolina’s Two Largest Counties Quit ICE Program. Will a Third Follow?" by Daniel Nichanian

The left had a very good election night when it came to big city and county offices that handle law enforcement; here's one look at the effects.

"What Happened in the Georgia Gubernatorial Election?" by Catalist 

A data dive on the 2018 election that, perhaps more than any other, set the terms for competitive races in diverse and growing states.

COUNTDOWN

... 159 days until Kentucky's primaries
... 236 days until Mississippi's primaries
... 329 days until Louisiana's primaries
... 417 days until the Iowa caucuses