Watch Obama drop the hammer on GOP lawmakers who denounced Trump: 'Why are you still endorsing him?'

President Barack Obama on Tuesday came out swinging against Republican presidential nominee Donald Trump -- and he even said that Republican leaders should consider rescinding their endorsements of him.

"The Republican nominee is unfit to be president... and he keeps proving it," Obama said during a press conference. "The notion that he would attack a Gold Star family that made such extraordinary sacrifices on behalf of our country, the fact that he doesn't appear to have basic knowledge of critical issues -- in Europe, the Middle East and Asia -- means that he's woefully unprepared to do this job."

Obama then turned his attention to Republicans who have loudly condemned Trump for his statements about the Khan family while continuing to support his candidacy.

"I think what's been interesting is the repeated denunciations of his statements by leading Republicans," Obama said. "And the question I think you have to ask yourselves is, if you are repeatedly having to say, in very strong terms, that what he has said is unacceptable, why are you still endorsing him?"

Check out Obama's full challenge to Republican leaders below.