Republican presidential nominee Donald Trump arrives at Republican National Committee headquarters in Washington on May 12.  (Andrew Harnik/Associated Press)

En masse, foreign policy professionals and business leaders who would ordinarily vote for the GOP presidential nominee are not only rejecting Donald Trump but lining up behind Hillary Clinton.

Now it is 30 (!) former GOP members of Congress, including some big names (Vin Weber of Minnesota, Mickey Edwards of Oklahoma, Jim Leach of Iowa, Tom Campbell of California) and a respected senator, Gordon Humphrey of New Hampshire. They didn’t endorse Clinton, although they did leave the door open for doing so. They did, however, eviscerate Trump:

In nominating Donald Trump, the Republican Party has asked the people of the United States to entrust their future to a man who insults women, mocks the handicapped, urges that dissent be met with violence, seeks to impose religious tests for entry into the United States, and applies a de facto ethnicity test to judges. He offends our allies and praises dictators. His public statements are peppered with lies. He belittles our heroes and insults the parents of men who have died serving our country. Every day brings a fresh revelation that highlights the unacceptable danger in electing him to lead our nation.

They strike a blow against blind partisan loyalty:

Every day brings a fresh revelation that highlights the unacceptable danger in electing him to lead our nation. . . . It is in that spirit that, as Donald Trump’s unfitness for public office has become ever more apparent, we urge our fellow Republicans not to vote for this man whose disgraceful candidacy is indefensible. This is no longer about our party; it’s now about America. We may differ on how we will cast our ballots in November but none of us will vote for Donald Trump.

The letter, like similar ones, is aimed at Republicans who have been disappointed, and in some cases, stunned to see current party “leaders” fall in line behind a nominee many of them know to be unfit. They offer encouragement and confirmation to lifelong Republicans. No, you don’t need to vote for whomever the GOP comes up with, no matter what. No, country does come before party.

These sorts of letters matter to some key groups Clinton is trying to attract, including college-educated voters offended by Trump’s bigotry and ignorance. Such voters care about qualifications and credentials so the views of foreign policy, business and political leaders carry some weight. (These are the equivalent of the “Remain” voters in Britain for whom “expert” is not a term of derision.)

I suspect as we get closer to the election we will see more of these letters. There is safety — and media impact — in numbers.

With each of these letters, the current, elected Republicans who have acquiescenced to Trump and Trumpism look worse. People who sign these letters are in many cases the very people the Republicans look to for advice; the latter know the signatories are men and women of sound judgment. The moral and intellectual timidity of those who’ve given in to Trump depresses many conscientious conservatives who see only a precious few of the current crop of elected Republicans (e.g., Sens. Mike Lee, Ben Sasse, Jeff Flake and Susan Collins and Reps. Ileana Ros-Lehtinen and Adam Kinzinger and Gov. John Kasich) standing up to Trump and his mob.

Even if these kinds of letters change not a single vote — and I think they will — they are worthwhile. They serve as a rebuke to the go-alongers in the party and set a standard of patriotism future elected leaders can aspire to. Moreover, it is never too late to do the right thing — if for no other reason than it is the right thing.