Four candidates for the Republican nomination have qualified for Wednesday night’s fourth presidential debate in Alabama, the Republican National Committee and NewsNation announced Monday.

Florida Gov. Ron DeSandis, former South Carolina Gov. Nikki Haley, businessman Vivek Ramaswamy and former New Jersey Gov. Chris Christie will face off in Tuscaloosa. Former President Donald Trump, the favorite for the presidency of the Republican party will not participate again like all the previous debates.

Monday’s announcement comes just six weeks before Iowa opens the curtain on the primary election that will decide the Republican nomination.

To advance to the Tuscaloosa stage, candidates had to meet the highest donor and vote criteria set by the Republican National Committee.

They had to have at least 80,000 unique donors, with at least 200 in 20 states or territories. They also had to get at least 6% in two national primary polls or one national poll and two polls in separate first-ballot states: Iowa, New Hampshire, South Carolina or Nevada.

At the same time, the Republican National Committee RNC asked candidates to sign a pledge pledging to support the president-elect of the Republican party.