A dozen GOP Senators urged President Donald Trump to send lawmakers final legislative language for a U.S.-Canada-Mexico trade agreement as soon as possible so that it can pass before Democrats take control of the House next year.

The lawmakers wrote in a Nov. 20 letter that they’re concerned that waiting until 2019 to send Congress draft legislative language will make passage “significantly more difficult,” as some Democrats have called for revisions. Senate Majority Leader Mitch McConnell of Kentucky so far hasn’t shown interest in considering the trade deal before the end of the year.

If the president pursues congressional approval this year, “we commit to working with you in a consultative manner to draft implementing legislation that could win our votes, as well as a majority in the House and Senate,” the senators wrote. The senators asked for the pact to be provided before Nov. 30.

All three nations are preparing to sign the agreement during the Group of 20 leaders’ summit in Argentina taking place from Nov. 30-Dec. 1. The trade pact will require approval from the U.S. Congress and lawmakers in Mexico and Canada.

The letter was signed by the following senators: Pat Toomey of Pennsylvania, Lamar Alexander of Tennessee, Steve Daines of Montana, Deb Fischer of Nebraska, Jeff Flake of Arizona, Ron Johnson of Wisconsin, Jon Kyl of Arizona, James Lankford of Oklahoma, Mike Lee of Utah, Rob Portman of Ohio, Ben Sasse of Tennessee and Ted Cruz of Texas.

The U.S., Canada and Mexico at the end of September reached a preliminary deal to update the North American Free Trade Agreement, which Trump had derided as a “disaster” that cost the U.S. jobs. Negotiators from the three countries worked around the clock to clinch an agreement so outgoing Mexican President Enrique Pena Nieto could sign it before his successor Andres Manuel Lopez Obrador takes office Dec. 1.

The letter underscores the new clout Democrats will yield after the party seized control of the House of Representatives in last week’s midterm election. Republicans have a majority in the Senate and will turn over control of the House to Democrats in January.

The new deal would be called the U.S.-Mexico Canada Agreement, or USMCA. Business leaders welcomed the pact, which staved off the risk that Trump would withdraw from NAFTA, as he has repeatedly threatened. Still, Trump could give six months’ notice of U.S. withdrawal from Nafta, which put pressure on Democrats to vote for the deal or let the trading bloc collapse.