The stage is set for Republican White House hopefuls to confront each other for the last time before the campaigns fan out across the country for a month.

Tuesday night’s debate in Milwaukee is billed as a discussion on Fox Business about economic policy and spending, although it’s certain to turn more broadly toward the larger race that is unfolding. Already, debate moderators have signaled that they are going to push for specifics and they consider government spending—on foreign policy, social programs and politics—within their mandate.

At center stage will be the pair of political newcomers who have upended the GOP Establishment’s hopes of a bloodless campaign. Ben Carson, the retired neurosurgeon, has been under fire for perhaps stretching the truth in his celebrated biography. Donald Trump, the real estate tycoon, also is heading to the debate that many mainstream Republicans never expected him to arrive at while still relevant.

But in this year of unpredictability among the GOP’s base, these candidates are the frontrunners, with others such as Sen. Marco Rubio of Florida, Sen. Ted Cruz of Texas and former Florida Gov. Jeb Bush chasing close behind. Tuesday’s debate is likely the last chance they have to confront their party’s unexpected favors before the Dec. 15 debate on CNN.

The first order of business for these candidates will be to try to force Carson to clarify after a rough few days. The first-time political candidate is facing allegations that he exaggerated parts of his biography. Specifically, some reports have cast doubt on claims that he was a violent teen and that he was offered a scholarship to attend the U.S. Military Academy at West Point. Carson has angrily dismissed the questions as attempts to smear a conservative—and then used those reports as fundraising pitches.

He might not be able to have such deflection if one of his rivals directly challenges him. “It only takes one of these things. You guys find one thread and you keep pulling. That’s all it takes to make these guys unravel,” said a top aide to a Carson rival.

Even so, Iowa is still months away, and voters are only now starting to tune in. As they do, they’ll see a topsy-turvy political season that has seen two major Republicans exit the race, others struggle to remind voters why they were once considered frontrunners and political novices stay in the top tier. Tuesday’s debate is likely to add even more uncertainty.

The top-polling candidates—Trump, Carson, Rubio, Cruz, Bush, former tech executive Carly Fiorina, Ohio Gov. John Kasich and Sen. Rand Paul of Kentucky—are slated to debate for two hours, starting at 9 p.m. Eastern on Fox Business. At 7 p.m., lesser-polling candidates will meet for a session with New Jersey Gov. Chris Christie, former Arkansas Gov. Mike Huckabee, Louisiana Gov. Bobby Jindal and former Sen. Rick Santorum of Pennsylvania.

This article was originally published by Time.com.