If Trump remains in the race until the convention, the GOP primary is not likely to be very close. While polls this early are not perfect predictions of presidential primaries, they are still a pretty solid guide.

But to figure out just how strong Trump’s odds of winning are, we can’t only look at the current national polls. Instead, we have to consult historical campaign dynamics (and ideally the reliability of state-level polls, too). In late August, we did some of this work for a piece on the inevitability (or lack thereof) of a Trump nomination. The math suggests that Trump has something around an 80 percent chance of winning the primary — though the precise number depends on how well we think historical polling records will inform the accuracy of polls for this cycle. This cycle is unprecedented in several ways, such as a former president running for his party’s nomination and the front-runner faces four sets of criminal indictments. We concluded that there is room for another candidate to stage a comeback.

But the door to a non-Trump nominee closes as time goes on. Primary elections are path-dependent contests; if a candidate can do well in Iowa, that may catapult him or her to success later on. But if the other candidates do poorly compared to expectations, and Republican voters wind up concluding Trump is their best option to beat Biden and the other candidates are all a bunch of losers in a nine-way tie for second, the contest will be over before Super Tuesday.

—Analysis by G. Elliott Morris of 538

Before tonight’s debate kicks off, 538, The Washington Post and Ipsos partnered once again to ask 5,002 likely Republican voters which issues are most important to them when deciding which candidate to vote for in the primaries, using Ipsos’s KnowledgePanel.

Of the 20 issues that we asked about, voters were most concerned about “getting inflation or increasing costs under control” (54 percent), a topic that Republican voters have been concerned about since at least the 2022 midterms, according our a previous collaboration with Ipsos. Among likely Republican primary voters, concern over inflation remains high since before last month’s debate, when 53 percent of respondents said it was among the most important issues to their vote, despite the addition of a few more topics to our questionnaire. Other issues that were top of mind for voters were “controlling immigration” (40 percent), “ability to beat Joe Biden” (23 percent) and “someone fighting against liberalism and the woke agenda” (22 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 538

The Republican presidential candidate with the most institutional support is the one who decided not to show up tonight: Trump. He has 364 endorsement points, according to 538’s endorsement tracker, which assigns a certain number of points to each endorsement a candidate gets depending on how prominent the endorser is. DeSantis is in second place, but way, way behind, with 43 endorsement points.

This is important because the candidate with the most endorsement points by the time of the Iowa caucuses usually wins the nomination. Given how strong Trump’s polling lead is at the moment, one of the few things that could (maybe) stop him is Republican party leaders closing ranks around another candidate. So far, there’s no sign of that happening.

—Analysis by Nathaniel Rakich of 538

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

The 5,002 likely Republican primary voters we polled using Ipsos’s KnowledgePanel expect DeSantis and Ramaswamy to perform best, out of the seven-candidate field. According to a five-point scale that we calculated using respondents’ answers (with 1 being “terrible” and 5 being “excellent”), likely voters expected both DeSantis and Ramaswamy to perform “very good” (3.44 and 3.43 out of 5, respectively). They thought Haley would perform third-best (3.40 out of 5) and Scott fourth (3.20 out of 5). All of this is fairly in line with their pre-debate expectations in August.

When it comes to which candidates respondents are interested in, Haley saw the biggest bump since our poll before last month’s debate — 31 percent are now considering voting for Haley, up from 25 percent. Although she now has the third-most prospective support, she’s still got a long way to go compared to Trump (66 percent) and DeSantis (49 percent). About 1 in 4 likely Republican primary voters are also considering voting for Ramaswamy and Pence.

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

—Analysis by Holly Fuong of 538

Outside of the Trump-critical wing of the Republican primary — featuring Christie and Hutchinson, with major appearances by Pence — most of the presidential field has tip-toed around Trump, careful not to attract his ire. But in the last couple weeks, some candidates have started taking on Trump more directly, jeopardizing their prospects as his running mate.

Trump was already unlikely to name a challenger as his VP pick. Of the 19 unique Democratic and Republican presidential nominees since 1972, only four selected a running mate who had run against them in the same year’s primary. And Trump is even more prickly about loyalty than his recent predecessors.

Last week, we analyzed the tweets of the six highest-polling Republican candidates (other than Trump) in 538’s national polling average. Until recently, DeSantis had hardly acknowledged the former president, mentioning Trump just once since Jan. 6, 2021. But that changed last week, when DeSantis published three critical tweets about Trump. Scott, meanwhile, has largely kept his social media tone neutral toward Trump, but we did see a rare direct criticism on the stump last week, when he said Trump’s suggestion that he’d seek a compromise on federal abortion legislation was the wrong approach. Haley’s tone toward Trump shifted earlier this summer, from cautious to directly critical.

Tonight could tell us whether these recent instances of criticism are the beginnings of a new trend in which the GOP field actually tries to topple the front-runner.

—Analysis by Leah Askarinam of 538