DeSantis remains Trump’s closest challenger, but his support has been dropping over the past several months: He currently trails the former president by nearly 40 percentage points in our national polling average.

With that drop have come some shake-ups in the DeSantis campaign. The campaign has laid off around one-third of its 92-person staff, with the latest cuts coming in July, according to ABC News. Changes stretched all the way to the top: DeSantis replaced his campaign manager with his governor’s office chief of staff. On top of that, some of his top donors have voiced concerns, saying they want DeSantis to recruit more major donors and take a more moderate approach on social issues.

All of that has made this debate crucial for DeSantis, both in terms of trying to chip away at Trump’s lead and proving to his supporters that he actually has a shot. He’s recruited a veteran debate coach and is getting advice from a supportive super PAC, according to The New York Times. That advice? Rather than attack the front-runner, DeSantis should “take a sledgehammer” to Ramaswamy who, unlike DeSantis, is rising in the polls. DeSantis won’t just be trying to win the debate tonight: He’s also aiming to push back against the rolling tide of news that hints at a flailing campaign.

-Analysis by Monica Potts of FiveThirtyEight

DeSantis and Ramaswamy, both newcomers to the presidential debate stage, will appear front and center on Wednesday night.

That's because where candidates will stand was determined by how they are faring in the polls.

More seasoned politicians, such as Pence or Christie, have been placed closer to the outer rim because of their more middling numbers so far. Hutchinson and Burgum will stand on either end.

-ABC News' Alexandra Hutzler

Money isn’t the be-all-and-end-all of political campaigns — but it sure helps, especially during the early phases of a primary. And in the 2024 pocketbook primary, the leaders so far are Trump (who raised $17.7 million in April, May and June) and DeSantis (who raised $20.1 million). These figures are striking, but you also have to account for how much time each candidate has been in the race. For instance, DeSantis jumped in in late May, so he had much less time in which to raise that money than Trump. Here’s a chart of who raised the most in the second quarter on a prorated basis.

But there’s also important context that those topline fundraising numbers don’t tell you. For instance, Burgum’s and Ramaswamy’s totals aren’t as impressive as they look — most of their fundraising came from their own wallets rather than from grassroots donors. Burgum self-funded $10.1 million of his $11.8 million haul, and Ramaswamy self-funded $5.0 million of his $7.7 million total.

On the other end of the spectrum, Scott is in better financial shape than his $5.9 million raised would suggest. That’s because he has more than $21 million cash on hand, thanks to money he carried over from his high-rolling Senate campaigns.

-Analysis by Nathaniel Rakich of FiveThirtyEight

One challenger to Trump has surged ahead — in ad buys, at least. Scott announced an $8 million ad buy this month. The bulk of that, $6.6 million, will go toward TV advertisements in early primary states Iowa and New Hampshire, according to the Washington Post. That’s on top of the $40 million ad buy planned by a super PAC supporting Scott that was announced last month.

Trump and DeSantis, the two front-runners, had dominated in early ad spending. But challengers like Scott have stepped up as they’ve tried to qualify for debates and raise name recognition in early voting states. Super PACs supporting Haley and Burgum have also increased spending recently. Stand for America Fund, Inc., which is aligned with Haley, spent $2.3 million on ads so far in August, while Best of America, which backs Burgum, has spent $2.1 million, according to reporting from NBC News.

Meanwhile, Trump-supporting PACs have spent millions on the former president’s legal fees as the number of indictments filed against him has risen to four. That will leave less money for spending on ads going forward, but Trump remains the top campaign fundraiser.

-Analysis by Monica Potts of FiveThirtyEight

Trump maintains a lead of 25 percentage points over his nearest competitor in Iowa, according to the latest polls.

DeSantis and Scott are both polling higher in Iowa than they are nationally, according to our polling average. Trump is polling about 10 points lower in Iowa than in national polls.

According to a July poll from J.L. Partners/DailyMail.com, only 51 percent of Iowa Republicans said their mind was made up. Forty-three percent said they could still be persuaded to support another candidate. Voters who said they plan to vote for Trump were the most likely to say their mind is made up, with 80 percent saying so compared with 37 percent of those who said they plan to vote for DeSantis and 11 percent of those who said they plan to vote for Scott.

Scott and DeSantis have the highest net favorability among Iowa Republican voters. Pence, Christie and Hutchinson are underwater.

In an early state poll from the Manhattan Institute conducted in July, Iowa Republicans are split on whether electability is important. Forty-six percent of Iowa Republican voters say that it is most important for Republican candidates to win elections and be in power, even if that means compromising or moderating their positions, while 45 percent said it is most important for candidates to stay true to their principles, even if that means losing elections.

Iowa Republicans also think that skipping primary debates shows weakness more than strength, according to a July Fox Business/Beacon Research/Shaw & Co. Research survey. Fifty-nine percent of Republicans said skipping the debate shows weakness, while 27 percent said it shows strength.

-Analysis by FiveThirtyEight