Former Illinois state Sen. Darren Bailey on Thursday was to launch his campaign officially for the Republican nomination for Illinois governor in next year's election.

Cook County Republican Party Chairman Aaron Del Mar will be Bailey's running mate.

They will officially make their campaign announcement at the Drake Hotel in west suburban Oak Brook at 4 p.m. Thursday.

Bailey easily won the GOP primary in 2022, defeating then-Aurora Mayor Richard Irvin. But Bailey went on to lose to Democratic incumbent Gov. JB Pritzker in the general election by 13 percentage points.

Bailey served one term in the Illinois Senate, and one term in the Illinois House of Representatives before that.

As a state representative, Bailey filed a lawsuit challenging Gov. JB Pritzker's authority to issue executive orders during the height of the COVID-19 outbreak in 2020, but lost the legal battles in that case.

Last year, Bailey challenged U.S. Rep. Mike Bost (R-Illinois) in the Republican primary, and lost.