Sen. Richard Blumenthal (D-Conn.) warned early Thursday that Donald Trump Donald John TrumpUS reimposes UN sanctions on Iran amid increasing tensions Jeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Trump supporters chant 'Fill that seat' at North Carolina rally MORE Jr.'s response in an email chain in which he arranges a meeting with a Russian lawyer will "haunt" him.

During an interview on CNN's "New Day," Blumenthal said the emails released by Trump Jr. are "bombshell evidence of criminal intent."

"What they show is ... interest and enthusiasm for working with the Russians on interfering in the election," he said.

There is more evidence that has to obtained, Blumenthal added.

ADVERTISEMENT

"No question that we are very far from criminal charges here and from proof beyond a reasonable doubt," he said.

"But if you're asking what's the significance of the emails, it is criminal intent."

Blumenthal said criminal intent is often the most difficult part of any case to prove.

"These words, 'I love it,' will haunt Donald Trump Jr.," he said. "I can see a prosecutor posing arguments repeating those words, again and again and again, because they show what the purpose and motive was of this meeting."

When pressed on whether the meeting rises to the level of treason, Blumenthal said it "could rise to the level of espionage and treason."

"If it involved participation in a conspiracy in effect to undermine the lawful functions of the United States government by a foreign power," he said, adding that Russia is a dangerous adversary.

His comments come after Trump Jr. on Tuesday released an email chain detailing his conversations about setting up a meeting with a Russian lawyer he was told had damaging information on then-Democratic presidential nominee Hillary Clinton Hillary Diane Rodham ClintonJeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Momentum growing among Republicans for Supreme Court vote before Election Day Warning signs flash for Lindsey Graham in South Carolina MORE.

The information “would incriminate Hillary and her dealings with Russia and would be very useful to your father,” reads one of the emails from music promoter Rob Goldstone, who acted as an intermediary to set up the meeting.

“This is obviously very high level and sensitive information but is part of Russia and its government's support for Mr. Trump,” wrote Goldstone.

In a June 3, 2016, email referring to the information on Clinton, Trump Jr. told Goldstone: “If it's what you say I love it especially later in the summer.”