There has never been a third party candidate to win a Presidential election, unless you count Lincoln in 1860 as one. The last "moderate" Republican to run an independent third party run was John Anderson in 1980. He received 6.6% of the popular vote and no electoral votes, but his voters denied Reagan a 47 state sweep. Biden is probably as weak as Carter was. However, the political spectrum has shifted leftward since that time. Unless Trump has moved the needle significantly with respect to black, Hispanic, Asian and Jewish voters, a third party candidacy could have a greater impact now than in 1980. Remember that about one third of primary voters chose someone other than Trump. If the donor base that supported Haley, DeSantis, and others decides to fund a "No Labels" party, that could put Biden, or whomever the Democrats choose in his place, over the top without higher levels of cheating than we saw in 2020 and 2022.
Interesting point on state sore loser laws...but the question is has there ever been a federal decision on those laws.
If not—and I think not—then if she ran that issue would have to be litigated—and the Supreme Court would be under no obligation to take the case.
That is a big risk for the “No Labels” party.
“ Unless Trump has moved the needle significantly with respect to black, Hispanic, Asian and Jewish voters, a third party candidacy could have a greater impact now than in 1980.”
Get 70% of the white vote and you won’t have to worry about the others.