The final four Republican candidates are gathering in Detroit Thursday night for the Fox News debate, where Donald Trump will try to maintain his dominant position less than two weeks ahead of crucial races that could effectively seal his nomination.
Trump previously boycotted a debate held by Fox News in Iowa after feuding with the network over its use of host Megyn Kelly as moderator, who Trump has belittled with misogynist insults over several months. Kelly is set to return as moderator on Thursday, but so far Trump looks like he'll attend anyway.
The debate comes ahead of a slate of races that include Kansas, Kentucky, Louisiana, and Maine on Saturday, Puerto Rico on Sunday, and debate site Michigan, Mississippi, Idaho, and Hawaii on Tuesday.
But those are mostly undercards before the definitive showdown on March 15, when Ohio and Florida host winter-take all primaries. If Trump wins both states it will become extraordinarily difficult to prevent him from locking down the nomination.
With that in mind, here's what to watch for on Thursday.
The Anti-Trump Offensive
Senators Marco Rubio and Ted Cruz devoted the entire last debate in Houston to savaging Donald Trump, and they threw out so many attacks over the night that it was hard just to keep track of them.
The front-runner mostly stood his ground, but the debate kicked off an anti-Trump offensive from his rivals that hasn't let up since. Rubio and Cruz seized on his initial refusal to disavow support from the Ku Klux Klan and David Duke, have accused him of defrauding students at his defunct Trump University program, and believe he's hiding potentially damaging information in his unreleased taxes, among many other things.
Donald Trump's White Supremacist Problem
In addition, numerous Republican elites have joined the fray in the last few days, pledging never to vote for Trump under any circumstances in a general election. Mitt Romney, the party's 2012 nominee, has also criticized Trump and is teasing a major speech on the race in Utah on Thursday.
It wasn't clear from the Super Tuesday results, however, where Trump won seven of eleven states and the most delegates, that these attacks have done any significant damage. Thursday will give Rubio and Cruz another chance to hack away. They could get a boost from a Buzzfeed report that resurfaced a Trump University blog post in which the billionaire real estate magnate sang the virtues of outsourcing jobs, a practice he regularly decries on the campaign trail.
Rubio and Cruz's Uneasy Truce
Why did it take until the last debate for candidates to start whacking Trump? For months, Rubio and Cruz, among others, were far more concerned with taking down each other in order to become the last one standing against the billionaire mogul.
After Tuesday's results, which were disappointing for both candidates, it's possible tensions could surface again. Cruz openly called on other candidates to drop out after he won his home state of Texas on Tuesday, while Rubio has said he will run in all fifty states with a particular eye towards Florida.
At this point, though, it looks likely that the only way to stop Trump is through a contested convention in which no one wins an outright majority of delegates. Some anti-Trump Republicans have even suggested that all candidates should stay in the race in order to increase the likelihood Trump won't clinch the nomination. Others, like Red State's Erick Erickson, have suggested Cruz and Rubio form a joint ticket before Florida with Cruz on top.
All this raises a lot of uncertainty about their relationship heading into the debate. Do they renew their efforts to push each other out of the race? Or focus all their fire on Trump again?
The Kasich Factor
With Dr. Ben Carson's announcement on Wednesday that he would stop campaigning, Ohio Governor John Kasich is the candidate with the most tenuous hold on the race.
So far he has steadfastly refused to budge, despite picking up few delegates and reportedly facing pressure from GOP leaders to bow out to help the anti-Trump effort. An Epic-MRA poll of Michigan's GOP race, which Kasich's team had highlighted last month as a key opportunity, showed him at just 8 percent support. Trump held the lead at 29 percent.
In the previous debate, Kasich stayed out of the Trump fray, which largely rendered him an afterthought heading into what would turn out to be a string of dismal losses and a close second-place finish in tiny Vermont on Super Tuesday. Will he try to take on Trump this time to showcase himself as a possible alternative? Could Rubio try to finish him off?
This article originally appeared on MSNBC.com.