During an event held Saturday at a campaign office in Key West, Garcia told supporters that Clinton "is under no illusions that you want to have sex with her, or that she's going to seduce you." Garcia was recorded by a "tracker" -- a person employed in politics to observe and record rival candidates -- and the footage was provided to the Miami Herald.
In a statement, Garcia said he is sorry for his "poorly worded comment about Secretary Clinton."
"My comments were intended to speak to Secretary Clinton's relentless focus on getting the job done, despite the unjust gender stereotypes and biases women in public life are frequently subjected to," Garcia said.
"Hillary Clinton is the most competent and qualified presidential candidate in the history of this country, man or woman and I'm with her, because I'm confident she will be one of our country's most effective leaders," he added.
The video, which was recorded unbeknownst to its subject and shot upside down, showed Garcia speaking in a hallway with unidentified individuals prior to his scheduled remarks to supporters. He made the offending comment while comparing Clinton to Lyndon B. Johnson.
"I believe that we're going to have -- I'll mention it when I speak -- I believe we're about to see the most consequential presidency that we've seen since Lyndon Johnson," Garcia said. "This is not because I think Hillary Clinton is the greatest ever. But I do believe she is extremely, exceedingly competent, and she -- I know this is going to sound weird to you, but to me, as somebody who studies history, she's going to be very similar to Lyndon Johnson.
He added: "Lyndon Johnson wasn't a particularly charming man, wasn't a particularly nice man: He would ask you nice, and then when you didn't do it, he made you do it. And Hillary is under no illusions that you want to have sex with her, or that she's going to seduce you, or out-think you."
Garcia is seeking a comeback in Florida's 26th Congressional District, which encompasses the Miami area. He lost re-election there in 2014 and is currently locked in a tight race with the Republican who unseated him, Carlos Curbelo.