A Fox News guest said Donald Trump Jr.'s emails could spell the end of his father's presidency.
Jim Kessler, a co-founder of the centrist Third Way think tank, said President Donald Trump may be able to win the media battle, but he isn't sure the administration can survive his legal challenges.
"It's a public battle in the press that they're doing pretty well, they don't know how to wage a legal battle," Kessler said. "I think we just crossed into a new zone of seriousness about these Russia allegations, and it's gone into a DEFCON 5."
The president's son has been battered by a series of damning New York Times reports about his meeting with a "Russian government lawyer" promising dirt on Hillary Clinton, and he preemptively released his emails with a business associate who set up the meeting.
"These are very, very disturbing emails," Kessler said. "This is basically dealing with Russian agents, Russian spies -- this smells a lot like collusion."
He said the evidence revealed in Trump Jr.'s emails could be damning.
"I think there is a there, there," Kessler said. "I'm not sure this administration lasts the entire term because of this, and it's getting worse every day."
Jared Kushner, the president's son-in-law and senior adviser, and Paul Manafort, his then-campaign chairman, were added by Trump Jr. to the email chain titled "Russia-Clinton-private and confidential" -- which puts both men in potential legal jeopardy.
"I also think that we just saw Donald Trump Jr. sort of abandoning Jared Kushner and Paul Manafort and going in his own direction," Kessler said. "You've got three very, very vulnerable senior people now not on the same page. I think this is trouble for them and deservedly so, frankly."