Rep. Seth Moulton (D-MA) said Tuesday that it would be “the definition of treason” if members of President Donald Trump’s administration are “conspiring with Russia.”

“if members of the administration are essentially conspiring with Russia either through the campaign earlier or now in the administration itself, I mean, look, Wolf, that’s the definition of treason,” Moulton told CNN’s Wolf Blitzer.

“Let me just be precise on this. You’re throwing out a huge word, treason. Explain exactly what your concern is,” Blitzer said.

“The definition of treason is putting the interests of our enemy ahead of our own,” Moulton replied. “It seems like there’s a lot of evidence that there are members of the administration who are more concerned about Russia’s goals than our own.”

Trump’s former National Security Adviser Michael Flynn resigned from his post late Monday, days after reports revealed that he spoke about sanctions with Russia’s ambassador to the United States on a call before Trump took office.

This contradicted members of Trump’s administration, including Vice President Mike Pence, who previously denied that Flynn and the Russian ambassador discussed sanctions during their conversation.

“This is a very, very serious affair,” Moulton said on Tuesday. “And while we need to understand what’s going on with Michael Flynn, we can’t let this little scandal or perhaps a big scandal at the moment let us lose sight of the much bigger scandal, which is what is the overall connection between Russia and the Trump administration.”

“Do you think Flynn acted alone when he made that phone call to the Russian ambassador in Washington?” Blitzer asked.

“I don’t think that anything in Washington happens alone,” Moulton said.