Sen. Cory Booker (D-N.J.) spoke with Rachel on Friday night’s show, and he framed the fight over the Supreme Court vacancy in an important way.

“I think that this is going to be one of the great integrity checks of whether people’s word, honor, and integrity really is going to be steadfast,” the New Jersey Democrat said. “I have no illusions — I’m not so starry eyed not to believe that this is a rough world of politics — but I do believe that many of my Republican colleagues should they go against what they said four years ago, they will not only do damage to their own sense of honor, but I think they’re going to do damage — further damage to the institution in and of itself.”

This strikes me as the proper way to frame the circumstances. To condemn GOP senators as hypocrites — highlighting the breathtaking differences between their stated 2016 principles and their apparent 2020 intentions — is accurate, but it’s also incomplete. The question isn’t merely one of consistency; it’s also one of honor and character.

And so, are there four Senate Republicans with the integrity to honor their own party’s principles from four years ago? One stepped up on Saturday.

Breaking with President Donald Trump and her party’s leadership, Maine Republican Sen. Susan Collins — perhaps the most endangered GOP incumbent — said the Senate should wait to vote on a replacement for the late Supreme Court Justice Ruth Bader Ginsburg until after the November election.

Another followed suit on Sunday.

Sen. Lisa Murkowski, R-Alaska, on Sunday became the second GOP senator to publicly oppose voting on a Supreme Court nominee before the November election. “For weeks, I have stated that I would not support taking up a potential Supreme Court vacancy this close to the election,” Murkowski said in a statement. “Sadly, what was then a hypothetical is now our reality, but my position has not changed.”

If four Senate Republicans break ranks on the GOP confirmation scheme, it will almost certainly derail the process and leave it up to the winner of the presidential election to fill the current Supreme Court vacancy. The trick, of course, is identifying two additional possibilities.

Many will be closely watching Sen. Mitt Romney (R-Utah), who has frequently expressed discomfort with some of his party’s more indefensible antics. Indeed, this may seem like ancient history, but it was earlier this year when Romney voted with Democrats to remove Trump from office as a consequence of the president’s illegal extortion scheme. Will the Utahan decide eight months later that the Senate should nevertheless jam through Trump’s choice, propriety be damned? We’ll soon find out.

But even if Romney resists party pressure and does the honorable thing, finding the fourth vote seems vastly more difficult. Sen. Lamar Alexander (R-Tenn.) seemed like a strong contender, in part because he’s retiring, and in part because he has a reputation as an institutionalist. The Tennessee Republican nevertheless endorsed his party’s scheme late yesterday.

Another contender is Sen. Chuck Grassley (R-Iowa), who’s not only seen as an institutionalist, but who also recently expressed public reservations about ramming through a Supreme Court nominee during an election season. The Iowa Republican, however, is also an unabashed partisan.

It’ll also be worth watching Sen. Cory Gardner (R-Colo.), who has the distinction of being the only Senate Republican running for re-election in a blue state this year. The Coloradan, who went along with his party’s scheme against Merrick Garland four years ago, could presumably improve his standing in his home state by showing some integrity, but given his partisan record, there’s no reason to assume he’ll be responsible.

All of this applies to Sen. David Perdue (R-Ga.), too, who’s also up for re-election this year — occasionally trying to present himself to voters as an independent voice — in an increasingly competitive state.

The Washington Post has a helpful online whip count, highlighting which senators are still in play. All things considered, I think the odds are in Republicans’ favor — looking for four GOP senators who put honor over party is asking a lot — but surprises happen.