President Trump on Tuesday night formally endorsed Sen. Luther Strange, who's up for reelection next Tuesday in Alabama.
Strange, 64, who previously served as state attorney general, has been temporarily filling the seat that was held by Jeff Sessions, who now serves as attorney general.
The incumbent is fighting a spirited battle to keep his seat against Roy Moore, a former Alabama Supreme Court chief justice and Rep. Mo Brooks, who has served in the House since 2011.
All three candidates have been tying themselves closely to Mr. Trump. Strange and Moore, for example, have ads promoting their desire to "drain the swamp."
Brooks recently released a controversial campaign ad that included audio of gunshots from the Alexandria, Virginia shooting that left House Majority Whip Steve Scalise, R-Louisiana, injured.
CBS News' Steve Chaggaris contributed to this report.