WASHINGTON (Reuters) - U.S. House of Representatives Speaker Nancy Pelosi on Tuesday conditioned her support for a new U.S.-Mexico-Canada trade deal on better enforcement of its labor provisions, defying pressure by the Trump administration to get the deal done quickly.

FILE PHOTO: Speaker of the House Nancy Pelosi (D-CA) speaks during a media briefing ahead of a House vote authorizing an impeachment inquiry into U.S. President Trump on Capitol Hill in Washington, U.S., October 31, 2019. REUTERS/Joshua Roberts/File Photo

Pelosi, who last week had predicted an imminent breakthrough in talks with U.S. Trade Representative Robert Lighthizer, changed her tone after meeting with major labor leader, AFL-CIO President Richard Trumka, who has been critical of the accord.

“We can reach an agreement on USMCA when the Trade Representative makes the new NAFTA agreement enforceable for America’s workers,” Pelosi said in a joint statement with House Ways and Means Committee Chairman Richard Neal after the two Democrats met with Trumka.

President Donald Trump and top administration officials on Tuesday heaped pressure on Pelosi and Congress to ratify the trade agreement through scores of coordinated interviews with talk radio stations and aggressive social media postings.

They are pressing for quick passage of the trade agreement that will replace the $1 trillion North American Free Trade Agreement (NAFTA), but have faced opposition from labor unions worried about losing jobs.

House Democrats say they are trying to shore up enforcement of the trade deal’s environmental and labor provisions, but Trump has accused Democrats of stalling approval for purely political reasons to avoid handing him any kind of victory.

On Tuesday, Trump accused Pelosi of being unable to get the bill “off her desk” and said she was “using USMCA, because she doesn’t have the impeachment votes,” the president said, without explanation.

Pelosi introduced Trumka at a meeting attended by about 40 newly elected Democrats at the Capitol on Tuesday, according to one source in the room. The union leader emphasized the need for solidarity at this “most critical” stage of negotiations and said the union remained concerned about Mexico’s ability to implement and sustain labor reforms.

Trumka told union members on Monday that NAFTA had been “a disaster for working people,” and while there had been some progress in negotiations with the White House, USMCA was not ready for passage.

Trumka said there was pressure to “fold on core issues” to secure a deal, but vowed not to let that happen.

“Getting this done right is more important than getting it done fast. So until the administration can show us in writing that the new NAFTA is truly enforceable, with stronger labor standards, there is still more work to be done,” he said, according to excerpts provided to Reuters.

Mexican Economy Minister Graciela Marquez said on Tuesday that she was optimistic the pact would be ratified “in a few weeks.”

“Representative Pelosi has the commitment on our part to convince the outstanding representatives and union leaders in the United States,” she said in an interview on local radio. “We have spoken with union leaders and we have made our commitment known.”

U.S. Commerce Secretary Wilbur Ross argued on Tuesday that the agreement included much tighter environmental provisions and worker protections than any previous U.S. trade agreement.

“We have no doubt that if Speaker Pelosi lets it come to the floor, it will pass overwhelmingly,” Ross told a talk radio program at the White House.

Before Pelosi’s statement, Senate Finance Committee Chairman Charles Grassley, an Iowa Republican, had predicted the trade agreement could be passed before Christmas.

The House Ways and Means Committee’s Neal also sounded upbeat earlier in the day, telling reporters House Democrats had narrowed their differences with the Trump administration and adding, “We all have the end zone in sight.”

Lighthizer’s office had no immediate comment on the later joint Pelosi-Neal statement.

The USMCA, signed by the three countries about a year ago in an effort to replace NAFTA, must be passed by lawmakers in all three countries.

Mexico has already ratified the new deal, while Canada says it is waiting to move in tandem with the United States.