Nancy Pelosi has delivered a message to Donald Trump.

It is that the president of the United States is going to face a formidable adversary when the next Congress convenes in January 2019. The presumptive speaker of the House delivered that message in a face-to-face smackdown with the president in an Oval Office meeting the two of them had with Senate Minority Leader Chuck Schumer.

Oh, Vice President Mike Pence was in the room, too, but he had a “non-speaking” role in this idiotic and awkward exchange.

Pelosi, a California Democrat, informed Trump he doesn’t have the votes in the House to finance the “big beautiful wall” along our southern border. Trump sought to tell her that he does; she responded — immediately — no, Mr. President . . . you do not!

Pelosi is an expert at vote-counting, which was one of the hallmarks of her first stint as speaker from 2009 to 2011.

Trump, meanwhile, doesn’t know how the legislative process works. He has no background in congressional relationships. He doesn’t understand the importance of seeking to cooperate with the legislative branch of government.

The president’s modus operandi is to dictate his desires and then expect everyone to follow him over the cliff.

The new speaker isn’t wired that way. She’s tough and she is asserting herself as she should.

Let us remember something else: The U.S. Constitution stipulates that the speaker of the House is No. 3 in succession to the presidency. It’s good to remember that as we enter the new year — and a new era — in Washington, D.C.