WASHINGTON — In the final days of negotiations over President Trump’s new North American trade deal, Robert Lighthizer, the top trade negotiator, made one more attempt to pressure House Democrats to get on board with the pact. He called Speaker Nancy Pelosi on Saturday saying he had booked a flight to Mexico to sign the revised trade agreement.

“Go ahead — go to Mexico,” Ms. Pelosi told Mr. Lighthizer, she later recounted in a private meeting with her caucus. “Visit the lovely anthropological museum and have a nice meal.” In other words: You won’t be signing a deal yet. Mr. Lighthizer canceled his flight, she said.

On Thursday, after months of haggling and significant revisions to satisfy Democrats’ demands, the House overwhelmingly approved the United States-Mexico-Canada Agreement by 385 to 41. The vote, coming one day after the House voted to impeach the president, was a rare feat of bipartisanship that gave Mr. Trump his biggest trade victory to date and gave Democrats a more progressive deal than any previously negotiated by their own party.

The agreement, also known as the U.S.M.C.A., was the product of an unlikely partnership between Mr. Lighthizer and Ms. Pelosi, whose caucus wielded enormous power given the need for congressional approval. Veering between cooperation and brinkmanship, the pair negotiated a deal that fulfills Mr. Trump’s pledge to rewrite the North American Free Trade Agreement while also satisfying nearly every Democratic priority, including strengthening environmental protection and labor standards.