President Donald Trump said Republicans who criticize potential tariffs on Mexico should be “ashamed” of themselves for undercutting the U.S. negotiating position.

Trump, speaking in an interview with Fox News that was broadcast Thursday night, took aim at House Speaker Nancy Pelosi, a Democrat, as well as Republicans he did not identify, for criticizing his threat to apply 5% tariffs on all imports from Mexico starting Monday.

“What they’re doing is they’re hurting a deal. They should be saying, we’re with the president, we’ll do whatever he wants to do, and Mexico would fold like an umbrella,” Trump said in the taped interview with Laura Ingraham. “Now I have these people, and I’m saying there’s some Republicans, too, I think they should be ashamed of themselves.”

The U.S. and Mexico are set to resume talks in Washington on Friday, aimed at reaching a deal to curb the flow of migrants through Mexico into the U.S. and avoid the tariffs being applied.