Washington (CNN) Mississippi Republican state Sen. Chris McDaniel is dropping his primary challenge to Sen. Roger Wicker to instead run in a special election for the open seat of retiring GOP Sen. Thad Cochran, he announced Wednesday.

Facing an early March deadline to decide on whether to run for the Senate this year, McDaniel two weeks ago announced he'd take on Wicker.

But days later, Cochran announced his retirement -- effective April 1 -- in a move that appeared designed to ensure McDaniel, who lost a bitter 2014 primary runoff against Cochran, wouldn't seek the seat.

Republican Gov. Phil Bryant is set to appoint a replacement for Cochran through November's elections. Then, in November, Mississippi will hold a "jungle" contest -- in which candidates will be listed without party identification on the ballot -- to fill the remainder of Cochran's term.

"By announcing early, we are asking Mississippi Republicans to unite around my candidacy and avoid another contentious contest among GOP members that would only improve the Democrats' chances of winning the open seat," McDaniel said in a statement. "If we unite the party now and consolidate our resources, we can guarantee Donald Trump will have a fighter who will stand with him."