Democrats aren’t laughing about Donald Trump anymore. He has them all but admitting defeat.

In a stunning admission, Hillary Clinton’s campaign manager predicts in an email that Donald Trump will become president if he wins the Republican nomination.

“If Donald Trump takes the Republican nomination, our party will lose more than the presidency,” Robby Mook writes to supporters.

“Years of progress will be ripped away. Obamacare will be repealed. Marriage equality will be rolled back. Get excited to visit the wall on the Mexico border — and get ready to pay for it if President Trump can’t magically get Mexico to cough up the cash for it.”

While Mook stokes fear over an apparently inevitable Trump presidency, he’s also panicking over a surging Bernie Sanders.

Late last night, Bernie Sanders’ campaign announced they’d raised $1.4 million from 50,000 donations in a single day. The day before, they announced that the Reddit community had contributed more than $1 million to his campaign.

There’s no denying this: His supporters are stepping up. They see a chance to win in Iowa and they’re willing to go all in for their guy.

“We can’t let Bernie Sanders’ supporters out-match us,” Mook concludes. “It’s not just about the nomination. It’s about what comes next.”

It’s just the latest email in which the campaign is hyperventilating about short funds and rival candidates.

In another earlier this month, Mook said he was “worried” and “annoyed.”

News just broke that Bernie Sanders is outspending us on TV in Iowa and New Hampshire by hundreds of thousands of dollars.

I’m worried, because last-minute ads could cost us this election. And I’m annoyed — because once again, they’re counting on this team staying on the sidelines. …

They’ve got more donors than we do, more contributions than we have, and if they keep up this pace on TV, they’ll be able to get their message out to more people than we can.

The latest poll from Iowa shows Clinton and Sanders are neck-and-neck.

A survey by NBC News/Wall Street Journal/Marist shows Clinton with 48% support and Sanders at 45% — a lead within the poll’s relatively large margin of error of 4.7 percent.