US President Donald Trump shakes hands with Speaker of the House Nancy Pelosi as he departs following the Friends of Ireland Luncheon in honor of Irish Prime Minister Leo Varadkar at the US Capitol in Washington, DC, March 14, 2019.

According to a copy of a letter obtained by CNBC, Lighthizer submitted a draft so-called Statement of Administrative Action, which would allow the Trump administration to send the trade deal to Congress within 30 days. President Donald Trump wants to quickly follow through on his pledge to overhaul trade relations with Canada and Mexico, but Congress still stands in the way of ratifying the United States-Mexico-Canada Agreement. The White House wants to ratify the deal this summer.

U.S. Trade Representative Robert Lighthizer sent a letter to congressional leaders on Thursday, kicking off the process of approving updates to the North American Free Trade Agreement.

The administration has put pressure on House Speaker Nancy Pelosi and Democrats to approve the trade agreement despite lingering concerns about the deal within the Democratic-held House. The speaker previously urged Lighthizer not to take the formal step to accelerate ratification until lawmakers had more time to iron out concerns with the White House, according to The Washington Post, which first reported the possibility of Trump making the move Thursday.

"The Trump Administration's decision to send Congress a draft statement of administrative action before we have finished working with U.S. Trade Representative Lighthizer to ensure the USMCA benefits American workers and farmers is not a positive step," Pelosi said in a statement Thursday. "It indicates a lack of knowledge on the part of the Administration on the policy and process to pass a trade agreement."

She added that Democrats "have been on a path" to voting "yes" on approving the deal, but said "it must be a path that leads to an agreement that delivers positive results for American workers and farmers."

The White House's decision to move forward more quickly than Democrats asked follows a tense meeting between the president and Democratic congressional leaders last week. Trump told Pelosi and Senate Minority Leader Chuck Schumer that he would not negotiate with them on legislation while House committees investigate him.

Democrats have raised several concerns about the agreement, including enforcement of labor and environmental protections and the deal's potential effect on drug prices.

As the administration pushes to approve the deal, Vice President Mike Pence met with Canadian Prime Minister Justin Trudeau on Thursday. While in Ottawa, the vice president promised the U.S. would "get the USMCA done this year."

Canada has cheered the Trump administration's decision earlier this month to lift tariffs on steel and aluminum imports from Canada and Mexico, which both countries opposed. Some Republicans in Congress had said they would not move forward with the agreement while the duties were in place.

Canada also took a formal step earlier this week to move toward ratifying the deal.

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