Illinois Republican Darren Bailey challenges Rep. Mike Bost

CHICAGO — Darren Bailey, the former Illinois Republican state senator who lost a bid last year for governor to Democratic incumbent JB Pritzker, is now running for Congress.

He filed paperwork with the Federal Election Commission on Tuesday to run against five-term incumbent Republican Rep. Mike Bost. Bailey is set to make a formal announcement at a Fourth of July event with 500 guests at his home in Xenia.

The downstate Illinois contest is set to be the most watched in Illinois in 2024 as it pits two far-right Republicans against each other.

Bailey is a southern Illinois farmer whose run for governor was endorsed by former President Donald Trump, and Bost is a five-term congressman and U.S. Marine Corps veteran who was also endorsed by Trump. The former president called Bost a “terrific representative” for the 12th District.

This is the first real contest for Bost, whose last primary challenge was in 2018. Bost has consistently won his district by double digits against Democrats, including in 2022 when he won by 50 points. Bost has more than $648,000 on hand, according to FEC records.

A Trump endorsement would be huge in the high-profile contest.

A person familiar with the Trump campaign said House Speaker Kevin McCarthy has told the former president that he supports the reliably conservative Bost, who also endorsed McCarthy’s election for the top House job.

Bailey’s team would also like an endorsement, though short of that would want Trump to remain neutral.

Trump likes to back winners, and he could be miffed that Bailey lost by double digits to Pritzker.

The governor’s race drew national headlines when Pritzker and the Democratic Governors Association spent $35 million on ads during the Republican primary to define Bailey as a far-right conservative against a more moderate candidate. That fueled the Republican base to get out the vote and secure Bailey’s place in the general election — and eased the way for Pritzker’s victory.

The ads also helped build Bailey’s image as a MAGA Republican. He has assembled a strong grassroots following and is seen in Illinois Republican circles as a formidable candidate against Bost.

The race is already creating tension within the GOP.

“Darren Bailey moved to a downtown Chicago penthouse to get blown out by JB Pritzker, now he’s back seeking another political promotion,” Chris Gustafson, a spokesperson for the National Republican Congressional Committee, said in a statement. “Mike Bost is focused on delivering conservative results for Southern Illinois and that's why voters will re-elect him.”

Bailey was possibly angling for Bost’s seat even before last year’s governor’s race was wrapped up. Flyers were distributed in the deeply conservative 12th District promoting Bailey even though it’s an area that Bailey had easily sewn up for the governor’s contest.

Bailey’s real challenge in the governor’s race was winning over the Democratic stronghold of Chicago, where the bulk of the state’s population lives.

The 12th District, meanwhile, voted for Trump 56 percent to 41 percent in 2020, and 55 percent to 40 percent in 2016.