Sen. John McCain, R-Ariz., promised Monday that Senate Republicans would be united against "any" potential Hillary Clinton Supreme Court nominee, though a spokeswoman later clarified he would judge any nominee individually.

"I promise you we will, we will be united against any Supreme Court nominee that Hillary Clinton, if she were president, would put up," McCain said in a radio interview on "The Dom Giordano Program" in Philadelphia. "I promise you. This is why we need the majority."McCain's comments raised questions about whether Republicans would consider any of Clinton's nominees, if she is elected president over the GOP nominee, Donald Trump.

McCain's spokeswoman later clarified that the senator based his comments on Clinton's past support of "liberal" nominees."Senator McCain believes you can only judge people by their record and Hillary Clinton has a clear record of supporting liberal judicial nominees," McCain spokeswoman Rachael Dean said in a statement. "That being said, Senator McCain will, of course, thoroughly examine the record of any Supreme Court nominee put before the Senate and vote for or against that individual based on their qualifications as he has done throughout his career," Dean said.

The campaign for McCain's re-election opponent, Rep. Anne Kirkpatrick, D-Ariz., criticized Dean's statement."

John McCain's staff can't walk back McCain's promise to obstruct any Supreme Court nominee not made by Donald Trump — he said what he meant, and meant what he said," Kirkpatrick spokesman D.B. Mitchell wrote in a press release.

Mitchell pointed to McCain's statement in a recent debate where he said he would prefer eight Supreme Court justices over an additional liberal justice.

"We only have eight Supreme Court justices, and I would much rather have eight Supreme Court justices than a justice who is liberal in keeping of the practice of Ruth Bader Ginsburg, Elena Kagan and the others who are liberal, and in my view — their actions, in my view are not in keeping with the Constitution," McCain said. "This is what makes this election a very, very serious election."

Republicans have blocked President Barack Obama's Supreme Court nominee, Judge Merrick Garland, from consideration this year. They have argued the American people should determine the direction of the court through the presidential election, drawing ire from their Democratic colleagues.Senate Minority Leader Mitch McConnell, R-Ky., has insisted the vacancy caused by Justice Antonin Scalia's death would not be filled by Obama.

McConnell said at a Sept. 29 news conference before the October break, "As I've said repeatedly the next president will be filling that vacancy and we'll have to see who that is."