Last month, the Montana Democratic Party filed a state court lawsuit to remove the Green Party nominee for U.S. Senate from the ballot. See this story. The Montana Green Party is ballot-qualified. In Montana, all qualified parties nominate by primary. The winner of the Green Party primary withdrew after the election. State law gave the Green Party the right to replace him with someone else. The party chose Robert Bard, who had lost the Green Party primary. The Democrats say Bard is ineligible because the Green Party didn’t vet him, but there is no such requirement in the law.
Montana state courts removed the Green Party from the ballot in both 2018 and 2020, after the Democratic Party challenged the party’s petition. Later the law that the Democrats had used the invalidate the petition was itself invalidated by the Ninth Circuit, so the Green Party got back on the ballot due to the Ninth Circuit decision.