The U.S. and Mexico are prepared to move ahead alone on a new trade agreement, and Canada may get left behind, a top White House official said Friday.

Kevin Hassett, chairman of the Council of Economic Advisers, told Fox News that the revised NAFTA agreement could end up being a bilateral rather than trilateral agreement if Canada doesn't come around soon.

"We're still talking to Canada. We're getting very, very close to the deadline where we're going to have to move ahead with Mexico all by themselves," Hassett said. "I'm a little surprised that the Canadians haven't signed up yet. They've got a really, really good deal that they should be participating in."

The deadline for Canada to come on board is likely Sept. 30, Hassett said at a Yahoo Finance conference Thursday in New York.