Lankford will run to finish the last two years of Coburn's term. Less than a week earlier, Coburn, who has been battling cancer, announced he would retire at the end of the current Congress.
Lankford is the fifth-ranking House Republican and chairs the House Republican Policy Committee. National Journal noted Monday that although he's an ally of House Speaker John Boehner (R-OH), Lankford does not always vote with the top House Republican. In October, Lankford voted against ending the government shutdown (Boehner supported that proposal).
Oklahoma Gov. Mary Fallin (R) has scheduled the special election to coincide with the 2014 midterm election.
Lankford made the announcement Monday as other prospective candidates opted out of running for Senate. Both Rep. Tom Cole (R-OK) and Attorney General Scott Pruitt (R) announced Sunday that they would not run for Coburn's seat.
Lankford, however, appears to face some opposition from prominent conservative outside groups like the Senate Conservatives Fund and the Club for Growth, which have both indicated that they would not support his candidacy.