The U.S. and Canada will likely announce a trade agreement in principle on Friday, even if the details of it will have tobehammered out later, two American sources with knowledge of the talks said Thursday.

The countries only began negotiating in earnest on Wednesday after the States and Mexico forged a bilateral deal, but have been working around the clock to try to meet a Friday deadline for including Canada.

Foreign Affairs Minister Chrystia Freeland said Thursday she had had “good, constructive, productive” discussions with U.S. Trade Representative Robert Lighthizer, while work by officials was bringing talks closer to the point of ministerial decision making.

An announcement is expected “with high-level areas of agreement” that would allow U.S. Trade Representative Robert Lighthizer to file notice to Congress, one person briefed on the discussions told the National Post.

Then the two sides would continue to negotiate, said the person, who asked not to be named to protect their relationship with government officials.

If it happens, the agreement announced Friday would “probably (be) just enough to say ‘We are not walking away.’ ”

Another source also briefed on some aspects of the negotiations said any statement would deal with the “parameters of an agreement in principle,” leaving the fine print to be worked out later.

“My impression is that there is good progress and I’m hopeful there is a deal, but it’s not done,” said the person late Thursday afternoon.

Asked if the talks were revolving around the key questions of American access to the Canadian dairy market and the U.S. demand to scrap a dispute-resolution section prized by Canada, the source said “the issues that people thought would be challenging are the last ones to be negotiated.”

The Americans are pushing to get a deal by Friday to allow Mexico’s outgoing president to sign it before he leaves office Dec. 1, while providing Congress the 90-day notice required before trade deals are signed.

But there is another requirement that the full text of agreements be made public 60 days in advance, which many experts say could allow for Canada to keep negotiating details well into next month.

Freeland has been in meetings in Washington with Lighthizer since Tuesday. Officials worked late into the night and again all day to find areas of common ground and compromise.

“This was another good, constructive, productive conversation with Ambassador Lighthizer and his team,” she told reporters during a pause in Thursday’s talks.

“We’ve moved into a very intense rhythm of the negotiations, where our officials are working hard preparing issues for some high-level ministerial decisions.”

With talks coming to a head, Prime Minister Justin Trudeau held a conference call Thursday with premiers to discuss trade-offs. Freeland planned to be on the call, as did Canada’s ambassador to the U.S., David MacNaughton, and Dominic LeBlanc, the federal minister responsible for intergovernmental affairs.

After the call, provincial leaders were tight-lipped on the details of the discussion.