President Biden’s pardon of his son Hunter is being met with outrage and dismay not only from Republicans but from lawmakers and others in his own party after news began to circulate Sunday night that the president was doing an about face on his vows that he would not be using the pardon power.

“While as a father I certainly understand President @JoeBiden’s natural desire to help his son by pardoning him, I am disappointed that he put his family ahead of the country,” the Democratic governor of Colorado, Jared Polis, said on X. “This is a bad precedent that could be abused by later Presidents and will sadly tarnish his reputation.”

A Democratic congressman from Arizona, Greg Stanton, also disagreed with the president’s decision. “I respect President Biden, but I think he got this one wrong,” he said in a statement. “This wasn’t a politically-motivated prosecution. Hunter committed felonies, and was convicted by a jury of his peers.”

The negative reaction, though, isn’t universal. President Obama’s former attorney general, Eric Holder, supported Mr. Biden’s decision, posting on X that “No USAtty would have charged this case given the underlying facts.” Mr. Biden attributed his decision to issue the pardon — which absolves the younger Mr. Biden of responsibility for both firearm and tax crimes, in addition to any other federal crimes he may have committed between January 1,  2014, and December 1, 2024 — to his conviction that his son, and by extension himself, were victims of a politicized justice system.

The president announced his decision late Sunday, just after the Biden family left Nantucket, where they spent their Thanksgiving holiday together. “It is clear that Hunter was treated differently,” Mr. Biden said of his son. “No reasonable person who looks at the facts of Hunter’s cases can reach any other conclusion than Hunter was singled out only because he is my son — and that is wrong.”

President Trump also took to social media calling the pardon a “miscarriage of justice” and asking if the same courtesy would be extended to those who were imprisoned for the January 6 riots. “Does the Pardon given by Joe to Hunter include the J-6 Hostages, who have now been imprisoned for years?” Trump wrote on Truth Social. “Such an abuse and miscarriage of Justice!”

Republican lawmakers also came out in a firestorm of opposition to Mr. Biden’s sudden reversal, contradicting previous statements he made saying that he would “abide by the jury’s decision” before his son was convicted in June.

“Joe Biden has lied from start to finish about his family’s corrupt influence peddling activities,” the chairman of the House Oversight Committee, James Comer, wrote in a post on X. “It’s unfortunate that, rather than come clean about their decades of wrongdoing, President Biden and his family continue to do everything they can to avoid accountability.”

The senior Republican senator from Iowa, Chuck Grassley, said he was disappointed in Mr. Biden’s 11th-hour decision. “I’m shocked Pres Biden pardoned his son Hunter bc he said many many times he wouldn’t & I believed him Shame on me,” Mr. Grassley wrote on X. Other Republican lawmakers at Washington had more pointed words for Mr. Biden.

“Joe Biden said he would not pardon his son for the crimes he has committed. He lied,” Senator Barrasso of Wyoming wrote. “Tonight’s pardon is wrong. It proves to the American people that there is a two-tier system of justice.”

“Today, Biden’s CRACKHEAD SON received a FULL and UNCONDITIONAL PARDON despite a promise that there would be no such thing,” Congressman Ronny Jackson of Texas said on X. “Biden and his admin are DISGRACEFUL LIARS!!”

Congresswoman Marjorie Taylor Greene of Georgia also weighed in on X, saying Mr. Biden has a double standard for criminal proceedings. “This pardon is Joe Biden’s admission that Hunter is a criminal. Biden tried to throw President Trump’s sons in jail, but he lets his son off free even though he’s a convict,” she wrote. “Joe Biden is a liar and a hypocrite, all the way to the end.”

In previous comments to Fox News during the election, Trump said that he “wouldn’t do anything that would be overt” with the younger Mr. Biden’s case if elected back into the White House. “I’ll bet you the father probably pardons him,” he also said. “Let’s see what happens. But he’s a bad boy.”