President Donald Trump’s argument in an interview that it was acceptable, and even common, to use opposition research from foreign governments threw a spotlight Thursday on how campaigns research opponents and whether they draw a line at foreign interference.

Trump said in a Wednesday interview with ABC News he would consider accepting “oppo research” from a foreign government and wouldn’t necessarily alert the FBI. He also said members of Congress “all do it, they always have.”

Lawmakers from both parties quickly pushed back on that characterization. Both parties have campaign staff and outside groups that work to uncover negative information about political opponents, but that research does not involve help from foreign governments.

“I’ve lost track of how many campaigns I’ve been a part of, but can say with 1,000 percent confidence that I, and the people I’ve worked with, have never received ‘dirt’ on an opponent from a foreign adversary, let alone solicited it,” said Shripal Shah, vice president of American Bridge 21st Century, a Democratic opposition research super PAC.

A spokesman for the GOP opposition research group, America Rising, did not respond to a request for comment.