On June 20, two Nevada voters filed a lawsuit against the Nevada Secretary of State, seeking a determination that Kennedy can’t be on the ballot as an independent because he is a registered Democrat in New York.  The lawsuit is in state court.  Rockenfeller v Aguilar, 24 OC 00011, First District.  UPDATE:  see this story.

No state has ever before denied a presidential or vice-presidential candidate ballot access based on how that candidate is registered.  Similar challenges failed in Pennsylvania in 2004, in 2020 in Arizona, and in 2020 in Idaho.

Nevada has had independent presidential and vice-presidential candidates in the past who had recently been registered members of a qualified party.  They include James Stockdale, Ross Perot’s running mate in 1992, who had recently been a registered Republican; and Peter Camejo, Ralph Nader’s running mate in 2004, who was a registered Green.  Also in 2016 Rocky De La Fuente was on as an independent for president in Nevada, and he was a registered Democrat.

Also John Anderson in 1980 was legally considered by his home state, Illinois, to be a member of the Republican Party, because he had voted in the 1980 Illinois Republican primary.  Also he continued to list himself in the Congressional Directory as a Republican, all through 1980.

As to the point that Kennedy is running as a party nominee in some states and an independent in others, the lawsuit fails to recognize that a “presidential election” in November is actually 51 separate elections, and the voters are voting for presidential electors in each of those 51 jurisdictions.  There is no formal link between these 51 separate elections.

Canada held general elections for Parliament in 2021 and also 2019.  There have been no general parliamentary elections since then.  In both 2019 and 2021, the leaders of five parties participated in debates.  See this wikipedia story.

In the 1980 presidential election, independent candidate John B. Anderson, who got on the ballot in all 51 ballots, had only been certified for the ballot in four states as of July 1, 1980.  This information is from an AP story, dated July 1, located by historian Darcy Richardson.  The states were New Jersey, Utah, Kansas, and North Carolina.  Furthermore, after he was certified in North Carolina, the Democratic Party sued to remove him, and although Anderson won that lawsuit, as of July 1 he was therefore not absolutely on the ballot in North Carolina either.

On September 9, 1980, the League of Women Voters, which was sponsoring the general election debates, invited him into the September 21 debate, because he met their polling requirement of 15%.  The League also required him to be on the ballot in states containing a majority of electoral votes, but the League accepted states in which the petition had been submitted; it did not insist on waiting for certification.