Following the lead of his lawyers, President Donald Trump on Tuesday said collusion "is not a crime."

"Collusion is not a crime, but that doesn't matter because there was No Collusion," Trump tweeted Tuesday.

Collusion is not a crime, but that doesn’t matter because there was No Collusion (except by Crooked Hillary and the Democrats)! — Donald J. Trump (@realDonaldTrump) July 31, 2018

The tweet, alluding to the federal investigation into Russian interference in the 2016 election that includes possible collusion between Trump's campaign and Moscow, came a day after the president's personal lawyer, Rudy Giuliani, in a media blitz, began making the same defense. Giuliani appeared on multiple television networks Sunday and Monday to stress the president's innocence and add that "collusion is not a crime."

For months, Trump had insisted that there was "no collusion" between his campaign and Russia. As recently as Sunday, the president went on a tweetstorm, writing that “There is No Collusion!”

In an interview with The New York Times last December, Trump repeatedly asserted that his campaign did not collude with Russia, while noting briefly that collusion is not illegal.

"There is no collusion, and even if there was, it’s not a crime. But there’s no collusion," Trump said.

Now, however, the president and his personal lawyer are doubling down on the idea that collusion, even if it did occur, isn't illegal.

In fact, there is no statute covering "colluding" with a foreign power. It is illegal, however, to conspire to violate laws, including ones barring foreign participation in elections.

In an indictment this month, special counsel Robert Mueller accused 12 Russian intelligence officers of conspiracy to hack computers and defraud the United States, alleging that people “known and unknown to the grand jury” participated in that conspiracy.

Meanwhile, Jay Sekulow, another of Trump's personal lawyers, told Fox News on Tuesday that Mueller's Russia investigation will find no evidence of collusion, before also stating that collusion is not a crime.

“There's not any evidence of any collusion here involving our client and the Russians,” Sekulow told Fox, adding that he and his team of lawyers had looked through 1.4 million documents related to the Trump campaign and the special counsel investigation.

“Rudy Giuliani was correct — collusion is not a crime,” Sekulow said. “Well, that's not just technically correct. I mean that’s actually the law. But there’s no violation of law, statute, rule or regulation that we have seen after reviewing this case for a year, and I think Bob Mueller will come to the same conclusion.”

The evolving argument from Trump and his lawyers comes just a week after Michael Cohen, Trump's former personal attorney, asserted that Trump knew in advance about a meeting at Trump Tower in June 2016 between his son Donald Trump Jr. and a Russian lawyer. Then-Trump campaign chairman Paul Manafort and Trump's son-in-law, Jared Kushner, also participated in that meeting.

A knowledgeable source told NBC News that Cohen is willing to inform Mueller that Trump Jr. told his father about the meeting, contradicting Trump Jr.'s congressional testimony in May 2017. Trump has also asserted he didn't know about the meeting.

On Monday, Giuliani, in a series of confusing media interviews, also accused Cohen, as well as Cohen's lawyer, Lanny Davis, of incorrectly describing the attendees of various meetings that involved top figures in the Trump campaign around that same time period. He also appeared to suggest that another meeting had occurred at some point before the Trump Tower meeting, in which participants purportedly discussed "strategy" for the meeting with the Russians, before attempting to clarify later in the day that there had been no strategy session.

A source familiar with the secret testimony of key Trump Tower meeting participants to the House and Senate Intelligence Committees told NBC News that none of them ever raised the issue of a strategy session to get ready for the meeting. Neither was such a session mentioned in their testimony to the Senate judiciary committee, which has been made public.

Democrats on Capitol Hill criticized Trump and his lawyers for their shifting assertions.

"I can't keep up with Rudy Giuliani's theories of defense. And they change almost by the hour," Sen. Dick Durbin, D-Ill., told CNN Tuesday. "Collusion at one point never happened, the next point if it happened it's not serious. It goes on and on."

Durbin added that the country has to wait for Mueller's investigation to be completed to know for sure.

"Whatever his conclusion is on the issue of collusion ,I will stand by it," Durbin said.

Sen. Richard Blumenthal, D-Conn., said the Trump team is playing word games.

"There is credible evidence that the president of the United States has committed obstruction of justice and possibly a conspiracy to undermine our elections," Blumenthal said. "That's simply the facts and the law. And Giuliani is trying to confuse and distract, playing word games, but at the end of the day, the special counsel is going to proceed methodically and meticulously in making the case."

He also said that despite Giuliani's attempts to clarify his various comments to the media, the president's team appears to have helped support a case that Donald Trump Jr. committed perjury in his testimony before the Senate Judiciary Committee. Blumenthal said he wants Trump Jr. to come back before the committee and clarify his statements.

"He either mislead or lied to our committee when he came to be interviewed, according to the mounting evidence from Michael Cohen from others, and from Rudy Giuliani himself," Blumenthal said.

Trump Jr.'s attorney, Alan Futerfas, disputed that idea in a response to Giuliani's comments Monday, saying that "we have investigated this matter for over a year and are in command of the facts."

"We are fully confident of the accuracy and reliability of the information that has been provided by Donald Trump Jr. in the various investigations," Futerfas said in a statement.

Sen. John Cornyn, R-Texas, who has been a supporter of Trump, told reporters on Tuesday that he has not seen proof of collusion, but efforts by Trump and his legal team to parse the legality of "collusion" aren't helping.

"It's not particularly helpful. There is no evidence of collusion that I’ve seen, but I think those sort of comments are not particularly helpful," Cornyn said.