President Donald Trump began Labor Day by bashing union leader Richard Trumka after he criticized the president’s policies over the weekend.

“Richard Trumka, the head of the AFL-CIO, represented his union poorly on television this weekend,” Trump wrote on Twitter. “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!”

Trumka appeared on Fox News Sunday with Chris Wallace and criticized Trump.

“Unfortunately, to date, the things that he’s done to hurt workers outpace what he’s done to help workers,” Trumpka said, complaining about the president’s tax cuts for big companies and his decision to cut health and safety regulations as well as overtime rules.

He said that although he was encouraged that Trump was renegotiating NAFTA, he was concerned that Canada would be cut out of the deal.

“It’s pretty hard to see how that would work without having Canada in the deal,” Trump said.

The labor chief said that his union was likely to support Democrats in the midterm elections.

“It probably will be Democrats because, unfortunately, Democrats support working people more than Republicans have,” he said. “We’d like to change that. But the reality is, Democrats support working people more than Republicans.”

In response, Trump boasted that unemployment was at a record low.

“Our country is doing better than ever before with unemployment setting record lows,” he said on Twitter. “The U.S. has tremendous upside potential as we go about fixing some of the worst Trade Deals ever made by any country in the world. Big progress being made!”

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