Rep. Adam Kinzinger said Wednesday that he would "hit the hard stop" on an email from a foreign government saying that it had negative information on a political opponent.
"Opposition research is one thing," the Illinois Republican told Jake Tapper on CNN. "It's how politics works.
"If you look at any presidential election, they spend millions on opposition research. That's fine, that's how the system works.
"But if an e-mail says the Russian government has information, that is when you hit the hard stop on it."
Kinzinger's comments came after Donald Trump Jr. released emails Tuesday ahead of a meeting last year with a Russian lawyer saying that it had damaging information on Democrat Hillary Clinton and that the Kremlin backed his father's presidential bid.
"I don't know exactly where espionage laws apply in this situation," Kinzinger told Tapper.
"What I do know in the very least is if I got an e-mail that said: 'Hey, Congressman Kinzinger, we have information on the government or on your opponent,' I would walk it to the FBI and say: 'We have a problem. Do you want us to do a counter-investigation on them?'
"No one should be going to this level in the democratic process," Kinzinger said.