For some Republican senators this year, it has been tough to say who they’re not voting for — and even harder to say who has their support.

Sen. Pat Toomey (R-Pa.), who technically supports Donald Trump’s presidential bid, spent 10 painful minutes the other day on live television trying to avoid saying who he’d vote for. Sen. Kelly Ayotte (R-N.H.) has said that she might write in Trump’s running mate, Indiana Gov. Mike Pence (R). Both senators are on the ballot themselves this year — and represent presidential swing states to boot.

UPDATE on Toomey: 

The problem is, as House Speaker Paul D. Ryan (R-Wis.) has said many times this election, our electoral system is functionally set up as a binary choice. You either vote for the Democratic or the Republican candidate, or you cast a third-party vote that basically boosts the electoral odds for the Democratic or Republican candidate’s opponent.

In other words, the prevailing political wisdom is that if you vote for a left-leaning third-party candidate, you’re probably helping the Republican by taking away a Democratic vote, and vice versa — that a vote for a right-leaning third-party candidate probably helps the Democrat by reducing the GOP total.

Sen. Lindsey O. Graham (R-S.C.) — who, we’ll note, lives in a safely red state — doesn’t seem too concerned about those critiques: He announced Tuesday that he had voted for independent conservative candidate Evan McMullin.

There’s a reason Graham is the first sitting U.S. senator to endorse — let alone vote for — McMullin. Voting for McMullin may get Graham out of an awkward 10 minutes of questions about who he’s voting for, and it won’t affect the final result. Though it isn’t without at least some political risk (after all, presumably Trump has at least a few supporters in Graham’s solidly Republican home state, which he’s expected to win easily.) Also, Graham isn't on the ballot today.

McMullin, a former CIA agent, got into the race in August as a conservative alternative to Trump. But it was far from viable. He remains a relative unknown, to put it mildly; in fact, there’s a fairly decent chance that this story is the first time you’ve heard of him.

In fact, he’s not even on the ballot in all 50 states.

McMullin, a Mormon and Utah native, is polling surprisingly well in Utah — where, as my colleague Aaron Blake explains, he could rob Trump of the state’s six electoral votes.

It’s no surprise that Graham is voting for someone other than Trump. Graham, who briefly ran for president last year, has been one of the most reliably anti-Trump voices in the Republican Party. He has called Trump a “jackass” and a “race-baiting, xenophobic, religious bigot,” and he has suggested that Republicans should kick him out of the party.

As the GOP primary field narrowed, Graham famously characterized the choice between Sen. Ted Cruz (Tex.) and Trump as a choice “between being shot or poisoned” — a line I’m officially nominating for quote of the election. Trump is no fan of Graham’s, either: Remember that time last summer when Trump read Graham’s cellphone number on live TV?

Graham may be the most vocal anti-Trump Republican, but he’s not the only Republican in Congress who strongly dislikes Trump. Still, he’s the only Republican openly talking about voting for a third-party candidate.

In fact, even as more of the Republican Party distanced itself from Trump in the final days of the campaign, many also made sure to say they're still voting for him.

Some of those come-back-around-ers might be worried about primary challengers in future elections. Others might covet a future in the upper echelons of the Republican Party, and they (probably accurately) calculated that voting for your party’s presidential nominee is a prerequisite for climbing the ladder.

Graham doesn’t seem to care about any of that. Or he may have calculated that as a senior member of the party, he’s just not constrained by those rules. And that’s why, in a nutshell, Graham has voted for McMullin for president even when the rest of his party wouldn’t dare to.

More from The Fix: