In anticipation of tonight’s debate, we partnered with Ipsos and The Washington Post to ask likely Republican primary voters what they think about tonight’s debate participants and the candidate field in general.

The 4,968 likely Republican primary voters we polled using Ipsos’s KnowledgePanel expect Ramaswamy’s performance to be best among the eight expected debate participants. According to a five-point scale that we calculated using respondents’ answers (with 1 being “terrible” and 5 being “excellent”), likely voters expected Ramaswamy to perform “very good” (3.59 out of 5). They thought DeSantis would perform second-best (3.51 out of 5) and Scott third (3.43 out of 5).

When it comes to whom respondents think they’ll place their votes for in the primaries, 65 percent are considering Trump and 52 percent are considering DeSantis. About 1 in 4 likely Republican primary voters are considering voting for Pence, Scott and Haley. The remaining six candidates we asked about fell below 25 percent.

We’ll be watching to see how the candidates fare tonight, and if debate watchers’ opinions on whom they’re considering voting for will change after tonight’s performances.

-Analysis by Holly Fuong of FiveThirtyEight

Before tonight’s debate kicks off, FiveThirtyEight, The Washington Post and Ipsos partnered to ask Republican voters about how they might vote in the upcoming Republican presidential primaries. Specifically, we asked 4,968 likely Republican voters which issues are most important to them when deciding which candidate to vote for in the primaries, using Ipsos’s KnowledgePanel.

We offered respondents a list of 16 issues and allowed them to select up to three. Of the topics that we asked about, voters were most concerned about “getting inflation or increasing costs under control” (53 percent of respondents selected this issue), something Republican voters have been concerned about since at least the 2022 midterms, according to a previous FiveThirtyEight/Ipsos poll. Other issues that were top of mind for voters were “controlling immigration” (36 percent), “someone fighting against liberalism and the woke agenda” (25 percent) and “ability to beat Joe Biden” (25 percent).

If tonight’s debate touches upon those top issues, voters might get some clarity on who they are considering voting for when primary season comes around.

-Analysis by Holly Fuong of FiveThirtyEight

At PolitiFact, this is our fifth presidential cycle. We’ve published more than 23,000 fact-checks since launching in 2007, all using our Truth-O-Meter, which rates claims on a scale from True to Pants on Fire false for the most ridiculous claims.

If PolitiFact is new to you, there are a couple of rules of the road.

First, we don’t fact-check every claim every candidate says. We couldn’t … we’d be dead.

We focus on claims that are particularly interesting, in the news or obviously potentially wrong. Our grading scale tries to measure both the literal truth and how voters might interpret a politicians’ words. So if Pence tonight claims that he and Trump “achieved energy independence” in their first three years in office, it can be more complicated to fact-check than you think.

In Pence’s case, yes, the United States did produce more energy than its citizens consumed during the Trump/Pence White House, but that was built on more than a decade of improvements in shale oil and gas production, as well as renewables. And the U.S. did not produce more gasoline than it consumed (which is maybe what you were thinking about). And if that’s not enough, even though the U.S. didn’t use all the energy it produced, it still imported a substantial amount of energy to serve domestic markets.

So far in this cycle, we’ve published 52 fact-checks of the GOP candidates. Our checks tend to follow the polling of the race. We’ve fact-checked Trump 17 times, DeSantis 14 times, Pence six times, Haley and Tim Scott each five times, and so on. We'll be drawing on those previous fact-checks, as well as the thousands of other claims we've vetted, throughout the night.

-Aaron Sharockman, PolitiFact

I flew to Milwaukee earlier this week to talk to some local voters and learn more about why the GOP decided to have its first presidential debate of the 2024 cycle in the state.

-Analysis by Galen Druke of FiveThirtyEight

The 2024 presidential election has been underway for months, but with tonight’s first Republican primary debate in Milwaukee, we’re kicking off a new phase of the campaign. In these final five months before voting begins, we’re going to have monthly debates, dashes through Iowa, big-money fundraisers — and probably a culling of the field.

Tonight’s debate will feature eight candidates. Front-runner Donald Trump, who has a 37-percentage-point lead in FiveThirtyEight’s national polling average, will not be among them, as he has opted to skip the debate. Instead, we will hear from Florida Gov. Ron DeSantis; entrepreneur Vivek Ramaswamy; former Vice President Mike Pence; Sen. Tim Scott; former U.N. Ambassador Nikki Haley; former Arkansas Gov. Asa Hutchinson; North Dakota Gov. Doug Burgum; and former New Jersey Gov. Chris Christie.

There are a few threads and tensions we’re going to be watching tonight. First, in the absence of Trump, will his challengers’ attempts to position themselves as a more favorable option fall flat? How will candidates make their case for being a better alternative to Trump without having the contrast on stage beside them? Secondly, what sort of friction will we see between the anti-Trump candidates and those running on more similar ideas or rhetoric?

We’ll keep an eye on all this and more. You’ll be hearing from the crew at FiveThirtyEight and ABC News — as well as some new friends at PolitiFact — throughout the night. The Fox News-hosted debate begins at 9 p.m. Eastern, and we have some colleagues on the ground in Milwaukee who will ensure you’re going in with everything you need to know.

Thanks for joining us. Stay tuned as we update the blog with real-time analysis, charts, thoughts, questions, ideas, idle fancies and more. Leading up until the debate starts, we’ll run through the state of the race so far. Once the debate starts, we’ll make sure we’re addressing everything happening on stage, including what issues the candidates talk about, who they attack, how they position themselves and what Americans think.

-Analysis by Maya Sweedler of FiveThirtyEight