Sen. Ben Sasse of Nebraska says he cannot vote for Donald Trump if he wins the Republican nomination–but has not endorsed any of Trump’s rivals–not even Sen. Ted Cruz (R-TX), who needs the help.

Former Republican nominee Mitt Romney throws bombs at Trump — recycling the lines that hurt him in 2012 — but has not bothered to boost his presumed alternative, Sen. Marco Rubio (R-FL).

The GOP elite is a rotting tableau of political cowardice.

Time was, an elected leader picked a primary candidate and stuck with him. If that candidate lost — well, then, honor and principle demanded they go down together, until the convention offered a chance to re-unify the party.

Now, however, like a gormless gaggle of liberal arts majors, the Republican brass are afraid to leave their “safe space.” Instead, they pick impotently at the probable party nominee in a pretentious fit of post-modernist pique.

Rubio, who talks about “unmasking” Trump — what a delightfully deconstructionist, “lit crit” phrase that is! — gave the game away when he said Friday that the Republican Party “will be split apart” if The Donald is the nominee.

Note the passive language: “will be split.” He daren’t take personal responsibility for that threat to quit the GOP if he loses. Trump, too, threatens to leave — openly — but demands he be treated fairly, not that he be guaranteed to win.

(Cruz, to his credit, says he will back the nominee, regardless.)

The case against Trump is, arguably, powerful, and growing stronger. But when the National Review put its best team together to make that case, they did not have the guts to back an alternative. That was before a single vote had been cast — before it was, arguably, too late.

Now Trump’s haters hide behind a false controversy over the KKK — as opposed to seizing on something actually offensive — legitimizing the worst tactics of the left.

An honest choice for the anti-Trump faction would be to back Hillary Clinton. But they lack the nerve. Instead, Mel Martinez, former RNC chair, fantasizes about voting for Joe Biden.

Another option: stop throwing tantrums about Trump and start building a serious congressional opposition, the kind that will do to Trump what it has been afraid to do to Obama for more than seven years. Or — organize an Article V convention, as radio host Mark Levin has proposed, to rebuild the foundations of our constitutional republic, regardless of who occupies the White House.

Don’t like Trump? Do something useful, other than mocking and moaning.

But — no. Most Republican leaders won’t take a side — not even their own.

After the comical charade of making Trump sign a pledge to their party, they have abandoned it, seeking petty consolation in liberal comedians.

In so doing, they are — unwittingly, and witlessly — making the best possible case for a Trump presidency.

They are showing, one final time, how few leaders are among them, how ripe the opposition has been for a hostile takeover.