WASHINGTON — President Donald Trump’s intervention into a criminal case connected to his own conduct drew fierce rebukes Saturday from Democrats and a few lonely Republicans, with calls for investigations and legislation.

But it remained to be seen if Trump’s most recent defiance of the conventions of his office to commute the 40-month sentence of political confidant Roger Stone, just four months before Election Day, would matter to voters grappling with a deadly COVID-19 surge and a national discourse on racial justice.

Shortly before heading out Saturday morning for his Virginia golf club, Trump made unfounded accusations against his political foes while taking another swipe at special counsel Robert Mueller’s investigation, which led to convictions for six Trump aides or advisers, including Stone, a larger-than-life political character who embraced his reputation as a dirty trickster.

“Roger Stone was targeted by an illegal Witch Hunt that never should have taken place,” Trump tweeted. “It is the other side that are criminals, including Biden and Obama, who spied on my campaign — AND GOT CAUGHT!”

Trump later wore a mask during a visit to a military hospital, the first time the president has been seen in public with the type of facial covering recommended by health officials as a precaution against spreading or becoming infected by the coronavirus.

Trump flew by helicopter to Walter Reed National Military Medical Center in suburban Washington to meet wounded service members and health care providers caring for COVID-19 patients.

As he left the White House, he told reporters: “When you're in a hospital, especially I think it's a great thing to wear a mask.”

Mueller sharply defended his investigation, writing in a newspaper opinion piece Saturday that the probe was of “paramount importance” and asserting that Stone “remains a convicted felon, and rightly so.”

Trump has long sought vengeance against the Russia investigation that helped define his first two years in office. And now that the pandemic has imperiled his reelection chances by crushing the economy and sending his poll numbers sliding, he has taken to testing the limits of his power in order to reward loyalty and fire up his conservative base.

The decision to commute the sentence of the 67-year-old Stone, who was convicted of lying to help the president and set to report to prison on Tuesday, was loudly celebrated by some in Trump’s orbit as a triumph over deep state prosecutorial overreach.

But the move announced Friday evening came over the advice of a number of the president’s senior advisers, who warned him it would be politically self-destructive to reward Stone for his silence.

Trump had long floated the idea of clemency for Stone — as well as for other associates in legal trouble, including his former national security adviser Michael Flynn and campaign chairman Paul Manafort.

The reaction from Democrats was swift and furious.

House Speaker Nancy Pelosi on Saturday called it “an act of staggering corruption,” saying legislation is needed to prevent a president from pardoning or commuting the sentence of someone who acted to shield that president from prosecution. House Intelligence Committee Chair Adam Schiff called it “offensive to the rule of law and principles of justice.”

And Trump’s Democratic challenger, Joe Biden, resurfaced a 2019 tweet in which he said that “Trump has surrounded himself with people who flout our laws — we shouldn’t be surprised that he thinks he is above the law.” He added: “Still true.”

Republicans largely stayed silent on the issue Saturday, reluctant again to challenge a president who remains very popular with rank-and-file GOP voters. But one loud voice was Utah Sen. Mitt Romney, who was also the lone GOP senator to vote to convict the president during his impeachment trial earlier this year.

“Unprecedented, historic corruption: an American president commutes the sentence of a person convicted by a jury of lying to shield that very president,” Romney tweeted Saturday.

Sen. Pat Toomey, a Pennsylvania Republican, signaled dismay with the commutation, saying in a statement Saturday that it was a mistake while calling the Russia investigation “badly flawed” and a source of “frustration.”

But most Republicans who did speak out about the decision supported it. Sen. Lindsey Graham, a Trump confidant, said Stone was convicted of a “nonviolent, first-time offense” and the president was “justified” in commuting the sentence.

Trump likely cannot afford more political damage. He is decidedly trailing Biden, per his campaign’s own private admissions, and his effort to reboot his reelection bid took another blow when his planned rally Saturday night in New Hampshire was postponed. Campaign officials had deeply worried about low turnout. While an impending storm was blamed for the cancellation, sunny skies were seen in Portsmouth an hour before the president had been due to arrive.