Here are the Republicans who aren’t going to Donald Trump’s convention

The Republican National Convention starts next week in Cleveland, but quite a few key attendees will be missing.

This, of course, is because of Donald Trump. The billionaire tycoon has been frustrating and flustering prominent Republicans since the moment he emerged as a frontrunner late last year. Their disagreements with Trump range from the political to the stylistic to the personal, but many Republicans who find their candidate unsupportable have decided on the same course of action.

They just won’t show up.

It’s not a choice that everyone can make. While GOP heavyweights who aren’t in office or running for reelection can pretty much do as they please, the pressure to fall in line with party decisions reduces the options of other members. There’s no greater example of this than House Speaker Paul Ryan, whose position as the de facto leader of the party has forced him to swallow his well-documented disdain for Trump and issue public endorsements.

The empty seats at the convention will only further illustrate the growing divide between the GOP’s leadership and its voters.

1) Any member of the Bush family: The politicians of the Bush clan, the GOP’s favorite quasi-dynasty, have especially fraught histories with Trump. He has repeatedly accused George W. Bush of lying about the Iraq War. He made piteously light work of Jeb when the former governor tried to challenge him in the primaries. At least in part due to his indecorous treatment of W and Jeb, Trump will be the first Republican nominee not to receive the endorsement of the senior Bush since he left the White House.

2) Two former Republican nominees: Neither Mitt Romney nor John McCain will make an appearance in Cleveland. One of the earliest controversies of the Trump campaign involved the candidate making disparaging comments about McCain’s war record. The Arizona senator has also said Trump has made his reelection campaign this year “the race of my life.“ The two men haven’t exactly seen eye to eye, though last month McCain extended a hesitant endorsement.

For his part, Romney says he can’t support the real estate tycoon because of his racist and demagogic statements. Bob Dole, the only other living former nominee, will attend the convention.

3) A few of Trump’s former primary opponents: Of the wide field of candidates who ran against Trump in the primary, the majority have fallen in line and endorsed their candidate. As of now, only Marco Rubio and Rand Paul have expressed that they won’t be in attendance. Both are running for Senate reelection, with Rubio’s Florida race feasibly having the ability to determine senate control. John Kasich is not currently up for reelection, but it’s unclear what his convention plans are.

4) Republican senators in tight races: As Vox’s Andrew Prokop has pointed out, Trump is likely to change the lay of the land in quite a few important down-ballot Senate races. Perhaps in order to stave off a “Trump effect” by hemming too closely to the nominee, Sens. Pat Toomey (PA), Kelly Ayotte (NH), Mark Kirk (IL), and Ron Johnson (WI) have either expressed their hesitation or outright stated that they will skip Cleveland.