U.S. House Speaker Nancy Pelosi (D-CA) holds her weekly news conference on Capitol Hill in Washington, U.S. June 13, 2019. REUTERS/Jonathan Ernst

WASHINGTON (Reuters) - U.S. House of Representatives Speaker Nancy Pelosi on Wednesday outlined several key impediments to congressional approval of a U.S.-Mexico-Canada trade agreement, as Canadian Prime Minister Justin Trudeau was set to arrive in Washington to push for final approval of the pact.

Speaking at a breakfast for reporters sponsored by the Christian Science Monitor, Pelosi did not provide any timetable for the House possibly taking up legislation to approve the massive trade pact. Citing concerns over enforcement tools, labor and environmental protections and provisions on pharmaceuticals, Pelosi said the deal cannot simply be “NAFTA with sugar on top.”