The backbone of the Republican Party national security establishment openly opposed Donald Trump for months before he was the GOP nominee, and his newfound status has done nothing to change their minds.

Not only that, these experts—veterans of wars, diplomatic fights, and congressional tugs-of-war—are now largely willing to break for Hillary Clinton.

The Daily Beast reached out to 121 foreign policy operatives who signed a March open letter opposing Trump on the basis of his national security positions. Of the 37 Republican foreign policy experts who responded, 19 said they were either certain to vote for Clinton or were leaning toward voting for the former secretary of state.

“Not only am I not voting for Donald Trump, but also I am not voting for any Republican who endorsed or supported Trump—be it for Senate, House, alderman, or county clerk. And yes, I will vote for Clinton, simply because to not vote, or to vote Libertarian, would be a half-vote for Trump,” said Ken Adelman, U.S. arms control director during the Reagan administration.

“The only thing Donald Trump has done since I signed that letter has been to confirm beyond the shadow of a doubt that he is unfit to be commander in chief. He needs to suspend his campaign until he can figure out what’s going on,” said Daniel Drezner, professor of international politics at Tufts University.

Trump’s ascension to the nomination has been a clarifying moment for many Republicans who once criticized him vigorously. As the reality of the general election has set in, many have fallen in line: Speaker Paul Ryan endorsed, for example, while Sen. Marco Rubio said he would speak on Trump’s behalf at the convention (before he decided he wouldn’t ).

Dr. Patrick Cronin, who served as a senior official at USAID during the Bush administration, rejected the allegiance to party over principle.

“Only one candidate has thought through America’s challenges, understands policy, has a positive and inclusive vision, is smart about the world in which we live, and is ready to be president, and I intend to vote for her—Hillary Clinton,” Cronin said.

Another sizeble segment, 17, said they would be writing in someone other than Trump or Clinton on Election Day.

Richard L. Russell, a special adviser at U.S. Central Command and a professor at National Defense University, will be writing in Jeb Bush. For Andrew Natsios, a Bush-era special envoy to Sudan, his symbolic choice will be Rubio. And for former House Armed Services Committee staffer John Noonan, the write-in will be retired Gen. Jim Mattis.

“I cannot vote for either presumptive nominee,” said Daniel Pipes, president of the Middle East Forum. “It’s a mild form of despair!”

Just one said they would vote for Trump.

“Primary is over. Hillary Clinton has a long government and foreign policy record indeed. And that record is filled with foreign policy disasters and unethical and possibly illegal behavior. I won’t cast a vote that would help her win the presidency,” the lone voice, who asked for anonymity, said.

Some Republican signatories were on the fence after Trump’s win in the GOP primaries, but his conduct since has alienated them—ultimately, forever.

“I considered supporting Trump for maybe a week. Then his slur of a U.S. judge’s ethnicity was utterly disqualifying. I would be ashamed to support him after that,” one of the letter’s signatories, who spoke on condition of anonymity, said.

The anti-Trump letter was written in early March, before Trump swept through Florida and ended Rubio’s presidential campaign, and well before Indiana’s vote sealed the fate of Sen. Ted Cruz. But for the vast majority of those who signed, #NeverTrump meant just that.

“I said ‘Never Trump’ and I meant it. If Secretary Clinton is the only viable alternative, I would expect to support her,” said Philip Levy, who served on President George W. Bush’s Council of Economic Advisers and as a member of Secretary of State Condoleezza Rice’s policy planning staff.

The paucity of support for Trump reflects the Republican’s unorthodox national security stances. He has slaughtered the sacred cows of the right’s traditional foreign policy philosophies by disparaging NATO and displaying an openness to Vladimir Putin; his anti-Muslim rhetoric contrasts sharply with the openness of the Bush administration toward America’s Muslim community; his policy on trade is to press America to turn in on itself, instead of opening up to new markets.

Trump’s current foreign policy team is essentially an island of misfit toys : a Christian academic accused of inciting anti-Muslim violence, a former DoD official who allegedly stood in the way of investigations into Bush administration bigwigs, and other so-called experts who are unheard of in established foreign policy circles. And the candidate’s seminal national security address, delivered earlier this month, was widely panned as full of errors .

By challenging Republican foreign policy’s long-held tenets, Trump has permanently estranged himself from the authors of those tenets. His campaign—and the Republican National Committee—will be emphasizing party unity in the coming months.

From the foreign policy perspective, at least, Trump will have to do without it.