President Trump called Monday for his former attorney Michael Cohen to serve a “full and complete” sentence, weighing in on the fate of a onetime loyalist who is arguing that he does not deserve prison time for the criminal charges to which he has pleaded guilty.

“You mean he can do all of the TERRIBLE, unrelated to Trump, things having to do with fraud, big loans, Taxis, etc., and not serve a long prison term?” Trump said in morning tweets. “He makes up stories to get a GREAT & ALREADY reduced deal for himself. . . . He lied for this outcome and should, in my opinion, serve a full and complete sentence.”

An attorney for Cohen declined to comment Monday on the president’s tweets.

In a late-night court filing Friday, attorneys for Cohen wrote that their client was a changed man who was cooperating extensively with special counsel Robert S. Mueller III as well as other prosecutors conducting probes related to Trump and his 2016 campaign.

Cohen pleaded guilty in August to five counts of tax evasion, one count of making a false statement to a bank and two campaign finance violations, admitting that he and the chief executive of a media company worked in the summer of 2016 to keep an individual from publicly disclosing information that could hurt Trump’s campaign. Two women had alleged extramarital affairs with Trump, which the president denies.

On Thursday, Cohen added an additional guilty plea, admitting that he lied to Congress about an ultimately unsuccessful effort to build a Trump building in Russia. He is expected to be sentenced Dec. 12, and prosecutors have to submit their own recommendation.

Trump lashed out at Cohen last week after his latest guilty plea, telling reporters at the White House that Cohen was a “weak person” and insisting that he himself had done nothing wrong on the Russian real estate project.

Cohen said that he had lied to Congress to minimize the links between Trump, who was seeking the Republican presidential nomination, and the Moscow project that Trump’s company was pursuing at the time.

Before last week, Trump had repeatedly said he had no business dealings in Russia, tweeting in July 2016, “For the record, I have ZERO investments in Russia,” and telling reporters in January 2017 that he had no deals there because he had “stayed away.”

In another tweet Monday, Trump praised another longtime associate, Roger Stone, who also has drawn Mueller’s scrutiny, for having said he would never testify against Trump.

“This statement was recently made by Roger Stone, essentially stating that he will not be forced by a rogue and out of control prosecutor to make up lies and stories about ‘President Trump,’ ” Trump wrote. “Nice to know that some people still have ‘guts!’ ”

The tweet about Stone drew immediate criticism from several lawyers, who said it amounted to witness tampering.

Among those who chided Trump was George Conway, the husband of White House counselor Kellyanne Conway and a frequent Trump critic. On Twitter, he referenced Trump’s tweet and wrote: “File under 18 U.S.C. §§ 1503, 1512,” citing sections of the federal code that deal with obstruction of justice and witness tampering.

Sen. Mark R. Warner (D-Va.) weighed in later.

“This is serious,” Warner, the vice chairman of the Senate Intelligence Committee, wrote on Twitter. “The President of the United States should not be using his platform to influence potential witnesses in a federal investigation involving his campaign.”

Trump also took fresh aim Monday at Mueller, who is investigating possible coordination between Trump’s campaign and Russia in the 2016 election and whether Trump has tried to obstruct the probe.

“Bob Mueller (who is a much different man than people think) and his out of control band of Angry Democrats, don’t want the truth, they only want lies,” Trump wrote. “The truth is very bad for their mission!”

Mueller, a Republican, was selected by Deputy Attorney General Rod J. Rosenstein, a Republican appointed to his position by Trump.