Scott Walker has said that he would support Donald Trump if he were the nominee, but the Wisconsin governor backed away from that pledge in the wake of Trump's racial attack on the federal judge overseeing a lawsuit against Trump University. Trump said the judge, an American citizen born in Indiana, was biased against him because "he's a Mexican."

"It's just sad in America that we have such poor choices right now," Scott Walker told a reporter from Wisconsin's WKOW on Tuesday. The news station reported that Walker "wouldn't say that whether would continue to endorse him going forward."

"He's not yet the nominee," Walker added. "Officially that won't happen until the middle of July and so for me that's kind of the time frame that, in particular, I want to make sure he renounces what he says--at least in regards to this judge."

On Tuesday, Illinois senator Mark Kirk became the first prominent Republican to fully withdraw his endorsement of Trump. "I cannot and will not support my party's nominee for President regardless of the political impact on my candidacy or the Republican Party," Kirk said. "After much consideration, I have concluded that Donald Trump has not demonstrated the temperament necessary to assume the greatest office in the world."