WASHINGTON >> President Donald Trump warned tonight of dire consequences should Democrats take the House in this year’s midterm elections, but predicted Republicans are “going to win.”

Speaking at the National Republican Congressional Committee’s annual March fundraiser, Trump said that, “on issue after issue,” House Democrats are “way outside of the American mainstream.”

“Democrats like to campaign as moderates, but they always govern like radicals,” he said, warning that, if they win, Democrats will block efforts to secure the borders, “release dangerous criminals,” and try to raise Americans’ taxes, among other ills.

He also vowed to campaign tirelessly to help GOP candidates win, telling a room full of Republican party leaders and donors, “I’ll be all over the country.”

The event, which was open to the press, provided a rare look at the kind of remarks that are typically made behind closed doors. Trump’s White House usually bars reporters from attending his fundraisers — though an audio recording of an event last week in St. Louis quickly leaked.

Tonight, Trump once again criticized Rep. Maxine Waters, D-Calif., as a “low-IQ individual” and went after House Democratic leader Nancy Pelosi.

“These days there are no such thing as a Blue Dog Democrat, a red state Democrat, or a conservative Democrat. Because they are all Pelosi Democrats: weak on crime, weak on terrorism and weak on national defense,” he said. He also pointed to his 2016 rival Hillary Clinton’s recent comment about women voting in line with their husbands, sons and male bosses.

“That was not a good statement,” he said to laughs.

During one riff, Trump talked about how he’d lifted a ban on oil and gas drilling in the Arctic National Wildlife Refuge. Trump told the crowd he hadn’t thought the issue was “a big deal,” until he got a call from a friend in the oil business after the GOP tax bill passed in December.

“Is it true that you have ANWR in the bill?’” Trump recalled the friend asking. “I said: ‘I don’t know. Who cares? What is that? What does that mean?’ … What’s the big deal if they did put it in?’”

Trump said the friend told him that “every single president” including Ronald Reagan had tried but failed to get it.

“I said, ‘You’ve got to be kidding, I love it now.’ And after that, we fought like hell to get ANWR.”

The event also featured a speech by House Speaker Paul Ryan, who said Republicans were making good on their promises with measures like last year’s tax overhaul.

“I know we can tell this story in our districts,” he said. “We will win this debate this fall. Mark my words.”

The event, which is the NRCC’s biggest of the year, raised $32 million, an all-time record, spokesman Matt Gorman said.