U.S. President Donald Trump says he would understand if the leaders of Canada and Mexico get tired of waiting on the United States to pass a new trade agreement among the nations. 

Trump said that would be a good deal to all three sides.

Trump made his comments during his bilateral meeting with Canadian Prime Minister Justin Trudeau on the sidelines of a NATO summit in London. 

Trump blames Democrats in Congress for stalling the agreement last week.

He said the U.S. House Speaker Nancy Pelosi, who insists on changes to the deal, is the one "incapable of moving" the agreement.

Pelosi wants changes to ensure improved labor and enforcement of environmental standards.