Sen. Mark Kirk (R-Ill.) speaks in Chicago after his win in the Illinois Republican primary Tuesday. (Kevin Tanaka/Chicago Sun-Times via AP)

Sen. Mark Kirk of Illinois on Friday became the first Republican senator to call for an up-or-down vote on Supreme Court nominee Merrick Garland, saying on a Chicago radio show that his colleagues ought to “just man up and cast a vote.”

That Kirk would be first to break with Senate Majority Leader Mitch McConnell (R-Ky.) and other GOP colleagues, who believe the next president should pick the replacement for Justice Antonin Scalia, is not particularly surprising: Kirk was already one of two Republican senators, with Susan Collins of Maine, to call for hearings.

Kirk faces what is perhaps the most difficult Senate reelection race in the nation — running during a presidential election year as a Republican in a state that hasn’t voted for a Republican president since George H.W. Bush in 1988. He is pitted against Rep. Tammy Duckworth (D), who has already sought to tie Kirk to national Republicans, including GOP presidential front-runner Donald Trump.

[Democrats plan push to force hearings on Supreme Court nomination]

Further complicating matters for Kirk is that Garland grew up in Illinois, in a Chicago suburb only a few miles from the border of the congressional district Kirk used to represent.

Kirk, speaking Friday morning on WLS-AM, said that the Senate “should go through the process the Constitution has already laid out” but that he did not see McConnell relenting before the election.

“I think given Mitch’s view, I don’t see his view changing too much,” Kirk said. “Eventually we will have an election, and we will have a new president, and the new president will come forward with a nomination.”

Among Senate Republicans, only Kirk and Collins have said they favor holding hearings on Garland’s nomination. Several others have said they would grant a courtesy meeting but only to inform Garland of their position against taking up his nomination.

Kirk, who said he admired Scalia’s approach to the law, did not indicate he had decided he would vote for Garland. He said he would question the appeals court judge on whether “the Constitution is a total living document that can change quite a bit.”

“Make sure the words mean the words,” Kirk said, explaining his views. “When it says freedom of speech, we should have freedom of speech — make sure the Constitution is something laid out in stone and so the common language of the words is what we understand them to be.”

Kirk’s comments come three days before Democratic activists plan a nationwide “Day of Action” to protest Republican senators who are opposed to taking up Garland’s nomination.

At least some Democrats were not impressed by Kirk’s willingness to break with McConnell: “If Senator Kirk were serious about fulfilling his constitutional responsibilities, he would publicly rebuke the strategy of the Republican Majority Leader he voted for, not predict the strategy’s success,” said Sean Savett, a spokesman for the Democratic Party of Illinois.

Correction: This file has been updated to correct the fact that Illinois last voted for a Republican president in 1988 not when Ronald Reagan last ran for president.

The Fix's Amber Phillips breaks down three ways the Merrick Garland nomination could play out. Which do you think is most likely? (Peter Stevenson/The Washington Post)