President Donald Trump on Tuesday morning issued a prebuttal to anything Michael Flynn, his former national security adviser and campaign aide, might reveal when he is sentenced by a federal judge later in the day.

The retired Army three-star general last year pleaded guilty to lying about his contacts with Russians during the 2016 presidential campaign cycle. Flynn once egged on Trump rally crowds in chants of “lock her up,” referring to Hillary Clinton’s use of a private email server while secretary of State.

A few years later, he became one of special counsel Robert S. Mueller III’s most cooperative witnesses, possibly providing damning information about the president and his family. Anything revealed in court documents or a verbal statement Tuesday will be closely watched by House Democrats, who take control of the chamber in a few weeks and are prepping a number of investigations of Trump and his 2016 White House bid.

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“Good luck today in court to General Michael Flynn,” Trump wrote in a tweet.

“Will be interesting to see what he has to say, despite tremendous pressure being put on him, about Russian Collusion in our great and, obviously, highly successful political campaign. There was no Collusion!” the president added.

Good luck today in court to General Michael Flynn. Will be interesting to see what he has to say, despite tremendous pressure being put on him, about Russian Collusion in our great and, obviously, highly successful political campaign. There was no Collusion!

— Donald J. Trump (@realDonaldTrump) December 18, 2018

Trump and Flynn grew close during the campaign, and the president has painted his cooperation with Mueller as the retired general looking out for his family amid “pressure” by federal investigators. That’s a big contrast to how Trump has referred to cooperation by his former personal attorney and “fixer,” Michael Cohen; in a tweet over the weekend, he called Cohen a “Rat.”

To be sure, Flynn has provided Mueller ample information on Trump and the 2016 campaign.

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In a sentencing memo filed last week, the special counsel described Flynn’s “substantial assistance.” He also recommended “a sentence at the low end of the guideline range — including a sentence that does not impose a term of incarceration — is appropriate and warranted.”

Many legal experts have said Trump, in the interest of his own potential legal jeopardy, should avoid commenting publicly on the Mueller probe. But Trump and his aides say he always will “fight back.”