Sen. Richard Blumenthal said Monday that President Trump's attacks against him prove the need for legislation protecting the special counsel leading the Russia investigation.

"I have no idea about what is in his mind," Blumenthal, D-Conn., said on CNN of Trump's critical tweets. "What I do know is I will not be distracted by this bullying. And these bullying tweets reinforce for me the need for a piece of legislation that I am helping to lead to prevent the firing of the special counsel Robert Mueller, who he has also sought to intimidate."

Last week, two bipartisan pairs of senators introduced legislation, endorsed by Blumenthal, to limit the executive branch's ability to fire a special counsel, requiring a panel of judges to review any such decision.

On Monday afternoon, Trump continued his criticisms of Blumenthal that started earlier in the day.

"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," Trump said on Twitter.

Earlier Monday, Trump criticized the Connecticut senator for saying he served in Vietnam when, in fact, he never did.

Instead, Blumenthal received five military deferments.

"Interesting to watch Senator Richard Blumenthal of Connecticut talking about hoax Russian collusion when he was a phony Vietnam con artist!" Trump tweeted. "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," the president continued. "Now he judges collusion?"

In response to Trump's tweets, Blumenthal accused the president of trying to bully him.

"Mr. President: Your bullying hasn't worked before and it won't work now. No one is above the law," Blumenthal tweeted Monday morning. "This issue isn't about me—it's about the Special Counsel's independence and integrity."

On CNN later Monday, Blumenthal again tried to downplay any personal dispute with Trump.

"There is an ongoing special counsel investigation," Blumenthal said. "It is real. It is based on facts. That's what is important. That focus is what really matters. Our national security and the rule of law are at risk, and that's where our focus should be. It is not about me."