MANCHESTER, N.H. — Former Attorney General Eric Holder suggested Friday that President Donald Trump has used his pardon power to try to send a message about the investigation into Russian election meddling without fully considering the ramifications.

“If you pardon someone, that means they don’t have much to worry about with regard to whatever the pardon covers,” Holder said. “But if (special counsel Robert) Mueller, for instance, wants to take that pardoned person and put that person in front of a grand jury, that person no longer has the ability to say, ‘I’m going to invoke my Fifth Amendment right'” against self-incrimination.

“That person then becomes a perfect witness for the special counsel,” Holder said. “And so it might have a positive impact on the person who received the pardon, but it will not ultimately thwart the Mueller investigation.”

Holder, a Democrat who is considering a bid for the White House, spoke in New Hampshire the day after Trump pardoned conservative author and filmmaker Dinesh D’Souza, who was sentenced in 2014 to five years’ probation for illegal campaign contributions. Trump said he’s also thinking about commuting the sentence of former Illinois Gov. Rod Blagojevich, who is serving a 14-year sentence for corruption, including trying to sell the U.S. Senate seat that was vacated by former President Barack Obama.

Holder said Blagojevich’s sentence was too harsh and he wouldn’t object to a shorter sentence. But in the case of D’Souza and others, he said, Trump is not following the usual metrics to identify good candidates for pardons, such as signs of contrition.

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Holder spoke at the “Politics and Eggs” forum at Saint Anselm College, which has traditionally attracted presidential candidates in the state that holds the first primaries. He said he will decide sometime next year whether to run, but in the meantime he is focused on his work as head of a group promoting fair election redistricting through support for like-minded candidates, lawsuits and other efforts.

In too many places, politicians are picking their voters instead of the other way around, Holder said. Such partisan gerrymandering — redrawing districts to give one party an edge — creates dysfunction in Washington, he said, because members of Congress who don’t have to worry about re-election see no need to listen to constituents or compromise with the other side.

Though he predicted a “blue wave” of Democratic wins in the upcoming midterm elections, Holder said, “That wave is going straight into gerrymandered systems in a lot of places, and the question is whether or not the wave will be strong enough to overcome the blocking.”