The Supreme Court on Tuesday declined to remove Robert F. Kennedy Jr. from the presidential ballots in two key battleground states, Wisconsin and Michigan.

Mr. Kennedy, an independent, suspended his campaign in August and endorsed former President Donald J. Trump. In emergency petitions to the court, he had mounted a last-ditch argument, saying the states had violated his First Amendment rights by keeping him on.

The decisions by the justices were unsigned and gave no reasoning, which is typical in such cases. There were no noted dissents in the Wisconsin challenge. But Justice Neil M. Gorsuch dissented in the Michigan case, echoing the reasoning of a dissent from an appeals court earlier in the litigation.

Since throwing his support behind Mr. Trump, Mr. Kennedy has sought both to be removed from and to remain on various state ballots. In September, the Supreme Court rejected a separate request from Mr. Kennedy asking that his name appear on New York’s presidential ballot.

Although early voting is already underway in both Wisconsin and Michigan, Mr. Kennedy asserted that he had acted in a timely fashion to try to remove himself from the ballots. Keeping him on, his lawyers said in asking the Supreme Court to intervene, compromised his “message of support for former President Trump.”

That he still remained only showed a disparity between how major-party candidates are treated versus independent candidates, Mr. Kennedy’s lawyers wrote, adding that Wisconsin allowed major-party candidates an extra month to adjust whether they appeared on the presidential ballot.

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