Welcome to FiveThirtyEight’s weekly politics chat. The transcript below has been lightly edited.

sarahf (Sarah Frostenson, politics editor): On Thursday, the House will hold its first formal vote of the impeachment inquiry into President Trump, signaling a new chapter in the impeachment investigation and perhaps an expedited timeline, with a full vote possible by Christmas.

So, let’s take a step back and start with the basics: Why are Democrats moving to hold a floor vote now after weeks of resisting one, especially considering the courts just ruled in their favor, saying the investigation was legal?

ameliatd (Amelia Thomson-DeVeaux, senior writer): I’m not sure how much of a legal benefit Democrats get from that court ruling, as the Trump administration’s arguments that the investigation is invalid were already on shaky ground. So I think one of the main functions of the vote is to outline what the rules for the public hearings will be, as well as possibly kneecapping Republicans who have been trying to condemn the inquiry because of a lack of a formal vote.

clare.malone (Clare Malone, senior political writer): I think there’s a real desire among Democrats to make this public sooner rather than later, too. There’s some sense that it’s been good practice to keep these initial hearings behind closed doors so witnesses don’t coordinate statements or what have you. But it can’t be behind closed doors forever! And I’m sure there’s a sense that the Democrats don’t want to give Republicans any more fuel for the fire of “secret, scary, due-process denying hearings!”

perry (Perry Bacon Jr., senior writer): I also assume Democrats are now comfortable taking a vote because the closed-door hearings have revealed a ton of questionable behavior by Trump and his administration. The vote to formally start the impeachment process will likely be interpreted by the public as a vote to impeach Trump. But I think the members, even in more moderate districts, now feel more comfortable taking that vote. An impeachment inquiry is no longer unpopular.

clare.malone: Impeachment is pretty popular! Though I find it interesting that there isn’t as much support for impeaching Trump and removing him from office.

ameliatd: It is also noteworthy that Democrats are willing to move on from closed-door hearings at this point. One of the big differences between this impeachment inquiry and the Nixon/Clinton impeachment proceedings is that the others were based on a preexisting criminal investigation where a special prosecutor had already done a lot of legwork to figure out exactly what happened. The Democrats have been doing their own investigation from scratch over the past few weeks. And that’s hard to do quickly!

sarahf: Another key distinction, though, is just how one-sided the support for impeachment proceedings are. It seems as if no Republicans will cross the aisle and vote in favor of this, right?

ameliatd: You’re right that other impeachment proceedings weren’t so one-sided at this point in the process. The vote to open an impeachment inquiry was overwhelmingly bipartisan in Nixon’s case (but Republicans didn’t really see that as an endorsement of impeachment and it took them a long time to fully abandon him), and quasi-bipartisan in Clinton’s case (about 30 Democrats crossed the aisle). But remember, in Clinton’s case, even that level of bipartisan support vanished pretty quickly.

So I think what this vote is really signaling is Democrats saying: 1) We’ve got what we need. 2) We’re ready to go public. 3) Here’s what the rules will be.

perry: Yeah, Democrats certainly seem to have what they need: evidence of impeachable offenses, pretty good polling and buy-in from the moderate members.

clare.malone: The idea of “we have what we need” is really key, given that in my view, a successful impeachment for Democrats is really about selling the public on their side of the story: the idea that Trump robustly abused power.

They’ll especially need that in a presidential election year, which makes everything very sensitive to begin with.

sarahf: On the question of moderate support, though, this stood out to me in some reporting from Politico:

Shortly after the vote on the resolution was announced Monday, several senior Democratic aides were struggling to explain the rationale, having been given little notice of it themselves and expressing concern about the long-term political impact it could have on the caucus’ most vulnerable members. Some moderate Democrats are already anxious about the plan, after making clear to leadership that they wanted to avoid any unnecessary floor votes on impeachment.

Do we think any Democrats break ranks in this vote? Isn’t the idea that this will be interpreted as a vote to impeach Trump by the public, as Perry said earlier, a real risk here for Democrats?

ameliatd: Well, it’s certainly possible. The last time the New York Times updated their whip count of who supports opening an impeachment inquiry against Trump, there were eight Democratic holdouts. That’s not a lot of Democrats who might remain opposed, but it’s also not a full consensus.

perry: I suspect all but a handful of Democrats will vote to authorize the investigation, and all but a handful will vote to impeach Trump. Maybe a few Democrats vote to investigate but not impeach, but even in a swing district, the overwhelming majority of Democratic voters are likely pro-impeachment. That makes it hard, I think, for a Democratic member to vote no on either the investigation or impeachment.

ameliatd: I’m also not sure how much this vote will matter vs. the ultimate impeachment vote. Maybe there’s a risk that if the Democrats really whiff on the public hearings, it will backfire on moderates, but I don’t know how much movement we’ll see between this vote and the vote to impeach, whenever that happens.

perry: Rep. Collin Peterson of Minnesota is in a very pro-Trump area, so maybe he votes against it.

Or Rep. Tulsi Gabbard of Hawaii. She is unpredictable and was an impeachment hold-out for a while.

ameliatd: But how much is at stake if only a handful of Democrats vote against opening the inquiry? I guess I think the bigger test will be the public hearings and how convincingly Democrats can marshal the evidence they’ve gathered.

perry: I agree. It doesn’t really matter.

clare.malone: Yeah, there’s not a lot of risk in this week’s vote, especially given Tuesday’s testimony from the top Ukraine expert on the National Security Council who was privy to Trump’s phone call with the Ukrainian president in July. There’s certainly some hang-your-political-cojones out there in the long-term if you’re a moderate Democrat, though.

But I think how Trump reacts to public hearings could give moderate Democrats cover in the weeks or months to come, similar to how once the Mueller investigation began to focus on Trump’s attempts to obstruct the investigation, he reacted poorly. I could easily imagine something similar happening here.

ameliatd: The Democrats are definitely trying to weaponize Trump’s reaction, and it’ll be telling to see how the public responds to that. Adam Schiff has essentially said that they’re not going to try to force testimony from White House officials who have refused to cooperate so far. Instead, they’ll just use that as evidence for obstruction of justice charges.

As I wrote on Tuesday, it’s definitely a pragmatic strategy for Democrats, as they just don’t have time to fight this in the courts. But it’s also potentially a little risky given that the obstruction of justice claims in the Mueller report didn’t lead to higher support for impeachment. Maybe it’ll be different this time?

perry: I actually don’t think the hearings matter? The evidence we have now is fairly extensive, and partisanship is very high. Are we suggesting the public hearings will make impeachment go up to 60 percent popularity or down to 40? How?

What Democratic voters are going to be break against impeachment? What Republican voters could be moved by the hearings (or anything else) to be for it?

clare.malone: I don’t think the hearings are going to make Republicans want it, Perry. But the hearings could bum Republicans enough to make them unenthusiastic. And depending on who the Democratic nominee is, maybe Republicans stay home, or perhaps they aren’t outraged enough by the nominee to vote against them and for Trump.

I think the hearings could be impactful in that way. They are, after all, going to create weeks of (likely) very unflattering news for the president. Is that nothing?

ameliatd: It’s also possible the hearings aren’t as dramatic or compelling as we’ve been led to believe, and so maybe some people who are in favor of impeachment conclude it’s actually not worth removing a president with less than a year to go until the election.

clare.malone: I’m not sure it necessarily has to be about dramatic moments in hearing rooms for it to have an impact, though.

I do think there’s a contingent of Republican and Republican-leaning independents who could be turned off by the whole thing. Again, who the Democratic nominee is has a lot to do with how that contingent acts. But it doesn’t need to be all drama, drama, drama to make waves electorally.

sarahf: So how does the Democratic nominee factor into all of this? It’s definitely one incentive for Democrats to move quickly, right? But how does the Democratic primary impact Republicans?

clare.malone: If Elizabeth Warren is the nominee, you’ve got a pretty motivated Republican electorate, and maybe the hearings matter less?

If it’s Biden, though, you’ve theoretically got a contingent of Republicans that are less concerned with coming out against the Democrats, and they might be more OK with staying home?

perry: I guess the one thing that I don’t quite understand is if the impeachment hearings are in December/January, that would certainly affect the Democratic nomination process, although I’m not sure how.

At the very least, the senators running would need to be in Washington, D.C. instead of Iowa.

clare.malone: Yeah, it’s poor timing!

ameliatd: It does seem increasingly likely that the impeachment trial will be in January, which is bad for the senators running. But it’s better to have the trial in January than have it stretch into February/March and suck up even more oxygen from other issues. And of course, the later it goes, the more it fuels the argument that an election is coming and the voters should decide.

clare.malone: It also risks making the race about Trump’s impeachment, which hasn’t necessarily been what voters in those early states want to hear about ALL the time.

Sanders made that point at the last debate, arguing that the candidates were getting sucked into the vortex of impeachment when they should be focusing more on the systemic issues facing Americans. I think that’s a valid, strategic view.

ameliatd: This is a hard issue for the Democratic candidates to weigh in on, too. There’s not a lot of daylight between them in terms of their stances on impeachment (as we saw in the debate), and it doesn’t really have much to do with their specific pitch for being president. So I’m sure they don’t want impeachment hanging over the primaries and, as Clare said, distracting from the other things they want to focus on.

sarahf: So does this move to formalize the vote change the nature of the impeachment investigation at all? I’m struggling with understanding the Democrats’ end goal. Is it to wrap this by the end of the year, hopefully by having moved public opinion enough that some Republicans break ranks?

Or if no Republicans break, is the goal to have released enough publicly damaging information about the president that it casts real doubts in voters’ eyes about his reelection prospects?

clare.malone: I think, honestly, in this age of hardcore partisanship, it’s more of the latter. It’s about an accumulation of bad information about him. It’s about depressing the vote on their side of things, not necessarily about persuasion.

And honestly, on some level, it’s about keeping their base happy.

ameliatd: I feel like we keep having these moments that seem like big news, but the day-to-day is functionally unchanged. The Democrats were always going to have public hearings, and it was going to be soon. This is a confirmation that they’re trying to move quickly, but it’s not a change in strategy.

clare.malone: Welcome to the NOTHING REALLY MATTERS team, Amelia!

ameliatd: Do we have hats? I would wear that hat.

clare.malone: MAKE AMERICA NIHILIST AGAIN.

ameliatd: But in terms of shifting support (maybe I am about to lose my NOTHING REALLY MATTERS hat), I think the hearings — and the narrative that emerges around them — will have more practical significance than the vote. Maybe not because it will be all-drama-all-the-time (we can only expect so much of congressional hearings), but because this is the Democrats’ window to strategically release into the open all of the damning evidence that they’ve gathered.

perry: These two votes will be among the most important these members take.

clare.malone: Their Iraq War Vote equivalent.

perry: Also, the skeptical Trump/Trump disapproval voters do matter, as Clare was getting at. If voting for Trump becomes something 15 percent of registered Republicans feel they can’t do, that’s a big thing.

If the evidence is so bad that Sens. Mitt Romney, Cory Gardner and Susan Collins vote to convict, that’s significant too.

clare.malone: Yeah, as we talked about on the podcast yesterday, some of these vulnerable GOP senators are in a real pickle.

sarahf: We’re probably still far way away from seeing any real break in the dam, especially if the House Republicans are unified in voting against the floor vote.

I do think, though, that one big risk in all of this for Democrats is if public opinion doesn’t move, or if support for impeaching and removing Trump from office drops after the public hearings start. That will complicate the narrative for Democrats.

ameliatd: True, none of this is to say that there’s no downside for the Democrats proceeding this way, especially if you look at a historical example like the Clinton saga, where support for impeachment did tick down as the inquiry wore on. But support for impeaching Clinton was also never consistently as high as it is currently for Trump. And if you buy the argument that some have made, that impeachment ultimately hurt Clinton and his party more than it hurt the Republicans, today’s Democrats are arguably in a pretty good position.