Sen. Richard Blumenthal said he will not be thrown off from talking about legislation designed to insulate special counsel Robert S. Mueller III by what the Connecticut Democrat called “slurs” being hurled at him on Twitter by President Donald Trump.

Mueller is overseeing the investigation of efforts by Russia to meddle in the 2016 presidential election, as well as of an expanding web of related activity that may prove criminal in nature.

“There is an ongoing special counsel investigation. It is real. It is based on facts. That is the important issue. That’s what really matters. Our national security and the rule of law are at stake,” Blumenthal said. “I am not going to be distracted or bullied by these slurs.”

[A Senator Out of His Shell, and Under Trump’s Skin]

Trump, who apparently was watching Blumenthal on CNN on Monday morning, called the senator a “phony Vietnam con artist!” in a tweet.

Interesting to watch Senator Richard Blumenthal of Connecticut talking about hoax Russian collusion when he was a phony Vietnam con artist!

— Donald J. Trump (@realDonaldTrump) August 7, 2017

That was a reference to a well-documented issue regarding Blumenthal’s military service, which came to light during his 2010 Senate campaign. While he served in the Marine Corps Reserve, he never served in country during the Vietnam War.

“Never in U.S.history has anyone lied or defrauded voters like Senator Richard Blumenthal,” Trump said in a series of tweets. “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?”

Never in U.S.history has anyone lied or defrauded voters like Senator Richard Blumenthal. He told stories about his Vietnam battles and….

— Donald J. Trump (@realDonaldTrump) August 7, 2017

…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?

— Donald J. Trump (@realDonaldTrump) August 7, 2017

Blumenthal responded during a routine Monday news conference at the Legislative Office Building in Hartford, Connecticut, that focused on the senator’s support for legislation introduced last Thursday by South Carolina Republican Sen. Lindsey Graham that would provide for a three-judge panel to review any attempt by either the attorney general or the acting attorney general to oust Mueller.

The bill led by Graham is one of two legislative efforts in the Senate seeking to give Mueller some protection through the judicial branch.

“Congress has the immediate imperative to make sure that the rule of law is upheld. The grand jury provides some permanence and protection because it’s an arm of the court, but this measure will be necessary, I fear, in light of the threats and intimidation that we see coming out of the White House,” Blumenthal said.

While he avoided the particulars of the misstatements about Vietnam, Blumenthal said the Trump tweets were just another signal of the likelihood that legislative action to protect Mueller may be required in short order.