The Michigan attorney general announced felony charges on Tuesday against 16 Republicans for falsely portraying themselves as electors from the state in an effort to overturn Donald J. Trump’s 2020 defeat there.

Each of the defendants was charged with eight felony counts, including forgery and conspiracy to commit forgery, on accusation that they had signed documents attesting falsely that they were Michigan’s “duly elected and qualified electors” for president and vice president.

“They weren’t the duly elected and qualified electors, and each of the defendants knew it,” Attorney General Dana Nessel, a Democrat, said in announcing the charges. “They carried out these actions with the hope and belief that the electoral votes of Michigan’s 2020 election would be awarded to the candidate of their choosing instead of the candidate that Michigan voters actually chose.”

The charges, the first against false electors in a sprawling scheme to hand the electoral votes of swing states won by Joseph R. Biden Jr. to Mr. Trump, add to the rapidly developing legal peril for Mr. Trump and those who helped him try to overturn the results of the election. They came the same day that Mr. Trump said federal prosecutors had told him that he is a target of their investigation into the Jan. 6, 2021, attack on the Capitol and other schemes he and his allies used to try to maintain power.

Those charged in Michigan included Meshawn Maddock, 55, who went on to serve for a time as the co-chair of the Michigan Republican Party. Ms. Maddock, who has close ties to former President Donald J. Trump and is married to Matt Maddock, a state representative, accused Ms. Nessel of “a personal vendetta.”

“This is part of a national coordinated” effort to stop Mr. Trump, she added.

Wright Blake, a lawyer representing Mayra Rodriguez, 64, another elector who is a lawyer, said in an interview: “I’m very disappointed in the attorney general’s office. This is all political, obviously. If they want to charge my client, how come they didn’t charge Trump and the Trump lawyers that he sent here to discuss with the delegates what to do?”

While a similar investigation in Atlanta has pulled in witnesses from across the country and has led to legal battles with Mr. Trump himself, thus far the Michigan inquiry has focused on residents of the state. It is not clear whether that will remain the case.

“This remains an ongoing investigation, and our department has not ruled out potential charges against additional defendants,” Ms. Nessel said Tuesday of her inquiry.

Others among the electors who were charged included Kathy Berden, 70, a member of the Republican National Committee, and Marian Sheridan, 69, the state party’s grass-roots vice chair. Neither responded to requests for comment.

Documents released Tuesday by Ms. Nessel’s office laid out a scheme in which many of the Trump electors convened at the Republican Party state headquarters on Dec. 14, 2020, after being turned away from the State Capitol. The real electors who were certified by the Board of State Canvassers did meet at the Capitol, as required by law. Yet the Republican group falsely claimed they were the rightful electors and had met at the Capitol.

Michigan is one of three states, along with Georgia and Arizona, where there are ongoing investigations relating to the use of false electors by the Trump team in 2020. Another investigation in Michigan, being conducted by a special prosecutor, concerns a network of right-wing activists — including Matthew DePerno, a Republican who ran unsuccessfully against Ms. Nessel last year — who are suspected of breaching voting machines in search of evidence of election fraud.

In total, allies of Mr. Trump pushed to convene slates of fake electors in seven swing states that Mr. Biden won. The plan was to create the illusion of a dispute over which slates — the fake Trump ones or the real Biden ones — were legitimate, and to have members of Congress and Vice President Mike Pence certify the fake Trump slates, thus handing the election to Mr. Trump in defiance of the will of voters.

Ms. Nessel began investigating the matter in early 2021, but referred it to the Justice Department in January 2022. She said at the time that while there were grounds to bring criminal charges, because there appeared to be “a coordinated effort between the Republican parties in various different states, we think this is a matter that is best investigated and potentially prosecuted by the feds.”

A few months later, she posted on Twitter: “If we don’t hold the people involved in the alternate elector scheme accountable, there is literally nothing to stop them from doing this again because there will have been no repercussions for it.”

But by January of this year, federal prosecutors had taken no apparent action. So Ms. Nessel announced that “we are reopening our investigation, because I don’t know what the federal government plans to do.”

In recent weeks, investigators have collected evidence and interviewed witnesses who have been affiliated with the state party.

Since Ms. Nessel reopened her investigation, federal prosecutors have become increasingly active in Michigan and appear to be treading similar ground. A number of elections officials and lawmakers — including the secretary of state, Jocelyn Benson — have reportedly been interviewed in recent months by federal prosecutors.

Both the federal and Michigan investigations are part of a reckoning over the conspiracy theories Mr. Trump and his allies have promoted about the election.