(Bloomberg) -- President Donald Trump abruptly canceled an outing on Monday to place calls on trade, his spokeswoman said, as he prepares to confront both China and Canada this week.

Reporters were summoned for the presidential motorcade Monday morning, but shortly after Trump emerged from the White House wearing golf attire, the trip was canceled and the press dismissed for the day. The White House didn’t say where he had planned to go. Trump spent much of the weekend at his northern Virginia golf club.

“The president stayed at the White House to make calls specifically on trade and other international issues,” Press Secretary Sarah Huckabee Sanders said in an email. She didn’t elaborate.

Trump’s trade negotiators are in difficult talks with their Canadian counterparts over a revision of the North American Free Trade Agreement already agreed to by the U.S. and Mexico. Over the weekend, Trump warned Congress that it may have to accept a new version of the trade pact that excludes Canada, a prospect with almost no support in either party.

As soon as Thursday, Trump may also implement tariffs on as much as $200 billion in additional Chinese products, escalating his trade war with the Asian powerhouse.

The president began his Labor Day holiday by attacking Richard Trumka, the president of the AFL-CIO, the largest U.S. labor union umbrella group. Trumka offered relatively low-key criticism of the Mexico-only approach in an interview on “Fox News Sunday,” calling Nafta in its current form “devastating” to American workers but questioning how it could be renegotiated without Canada.

“Our economies are integrated,” Trumka said on “Fox News Sunday.” “It’s hard to see how that would work without Canada on the deal.”

Trump, who said in a tweet over the weekend that keeping Canada in the pact isn’t a “political necessity,” belittled Trumka and the labor movement in a tweet. He has been counting on union support for his trade negotiations to pressure congressional Democrats into backing new agreements.

Richard Trumka, the head of the AFL-CIO, represented his union poorly on television this weekend. Some of the things he said were so against the working men and women of our country, and the success of the U.S. itself, that it is easy to see why unions are doing so poorly. A Dem!

— Donald J. Trump (@realDonaldTrump) September 3, 2018

The AFL-CIO didn’t respond directly. It posted a tweet on Monday recognizing Labor Day with audio from a Trumka speech that began, “We don’t fear the attacks against us.”

The Trump administration notified Congress on Friday that he planned to sign a trade deal with Mexico in 90 days, and that Canada would be included “if it is willing.” Talks are to resume between U.S. and Canadian negotiators on Wednesday, though Trump has indicated that he is unwilling to compromise on U.S. demands that include its northern neighbor dropping tariffs on American dairy products and eliminating a dispute resolution mechanism in Nafta.

“If we don’t make a fair deal for the U.S. after decades of abuse, Canada will be out,” Trump said in a tweet on Saturday. “Congress should not interfere w/these negotiations or I will simply terminate NAFTA entirely & we will be far better off.”

The White House didn’t respond Monday to questions about the Canadian negotiations and whether any U.S. lawmakers of either party support the president’s position.

--With assistance from Candice Norwood and Shawn Donnan.

To contact the reporter on this story: Justin Sink in Washington at jsink1@bloomberg.net

To contact the editors responsible for this story: Alex Wayne at awayne3@bloomberg.net, Margaret Collins

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