John McCain
Arizona Senator John McCain warned Republicans will continue to block Supreme Court nominees if Hillary Clinton is elected presidentWin McNamee/Getty Images

Arizona Senator John McCain vowed on Monday (17 October) that Republicans would not confirm any Supreme Court nominees chosen by Hillary Clinton if she wins the election. The Republican senator's comments were later softened by a spokeswoman.

"I promise you that we will be united against any of the Supreme Court nominees that Hillary Clinton, if she were president, would put up," McCain told a Philadelphia radio programme.

McCain, who was campaigning on behalf of Pennsylvania Senator Pat Toomey added: "I promise you. This is where we need the majority and Pat Toomey is probably as articulate and effective on the floor of the Senate as anyone I have encountered." According to US News & World Report, both senators are facing competitive challenges to re-election to their seats.

A spokeswoman for the Arizona Republican later clarified that he would still judge nominees based on their records and not on politics, the Wall Street Journal reported.

"Senator McCain believes you can only judge people by their record and Hillary Clinton has a clear record of supporting liberal judicial nominees," spokeswoman Rachael Dean said. "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."

McCain's remarks are a look at the partisan fight next year over the replacement of Justice Antonin Scalia regardless of who wins the White House. Senate Republicans previously said they would not fill the vacancy until voters elect a new president. However, McCain's comments suggest Republicans may drop that strategy and instead deny any nominees chosen by a Democratic president.

Either approach will be contingent on Republicans retaining control of the Senate. The GOP hold 54 seats in the Senate to the Democrats' 46, which include two independents who caucus with them. Democrats needs to win just four seats if Clinton is elected in order to take the majority.

According to FiveThirtyEight, Democrats have a 74% chance of winning control of the Senate. Analysis by the site noted that Republican seats in Pennsylvania, Missouri, New Hampshire, Indiana, Illinois, Wisconsin have high chances of switching from Republican to Democrat.

The race in the House of Republicans is not as clear-cut, though chances of Democrats flipping the House are not believed to be as far-fetched as they once were.