President Donald Trump on Monday morning called Democratic Sen. Richard Blumenthal a "phony Vietnam con artist" shortly after the Connecticut lawmaker appeared on CNN to push for passage of legislation to try and block Trump from firing special counsel Robert Mueller.

And then later in the day, Trump tweeted "I think Senator Blumenthal should take a nice long vacation in Vietnam, where he lied about his service, so he can at least say he was there."

Blumenthal was interviewed on CNN earlier in the day about several topics, including the Justice Department's crackdown on leakers, new sanctions on North Korea and reports that Mueller has impaneled a grand jury in his inquiry into Russia meddling in the election and potential ties to the Trump campaign.

"Interesting to watch Senator Richard Blumenthal of Connecticut talking about hoax Russian collusion when he was a phony Vietnam con artist!" Trump tweeted after the interview.

It wasn't the first time that Trump had raised the issue of Blumenthal and Vietnam. He brought it up after Blumenthal called for a special counsel following Trump's firing of former FBI director James Comey, and after Blumenthal said Judge Neil Gorsuch, who was confirmed to the Supreme Court, told him that he found the president's attacks on the judiciary "disheartening" and "demoralizing."

Blumenthal had to apologize after he stated, on at least several occasions, that he had served in Vietnam when he actually was posted stateside with the Marine Corps Reserve during the war. Blumenthal's service record became an issue during a hotly contested race for Senate in 2010 between him and Linda McMahon, who is now head of the federal Small Business Administration.

Blumenthal reportedly received at least five deferments from military service before going on to serve in the reserves. Trump reportedly received five deferments; four for college and one for bad feet.

"Never in U.S. history has anyone lied or defrauded voters like Senator Richard Blumenthal. He told stories about his Vietnam battles and.......conquests, how brave he was, and it was all a lie. He cried like a baby and begged for forgiveness like a child. Now he judges collusion?" Trump wrote in two successive tweets Monday morning.

Blumenthal, during a phone interview Monday afternoon, avoided commenting directly on Trump's criticism, saying "there's an ongoing special counsel investigation. It is real. It is based on facts. That is the important issue. That's the focus that matters."

But on Twitter, he wrote, "Mr. President: Your bullying hasn't worked before and it won't work now. No one is above the law."

Blumenthal, a member of the Senate Judiciary Committee, worked with other members of the committee on legislation that would prevent the firing of special counsels without judicial review. A three-judge panel, selected by the chief judge of the District of Columbia Court of Appeals, would have to determine that "good cause" exists to fire special counsels.

"When Congress reconvenes in September, I'm going to push for passage of this new law to protect a special counsel before the president's ominous threats become reality," Blumenthal said by phone Monday.

j.bergman@theday.com