Starr’s theory, which Trump has now fully accepted as his own, also recently appeared on Fox News, via Fox host Brit Hume, Fox contributor Trey Gowdy, and law professor and torture memo author John Yoo. Trump and Republicans hope to push the idea in order to get mail-in ballots received in Pennsylvania three days after Election Day tossed out because the expanded-deadline order came from the Pennsylvania Supreme Court, and not the state legislature. These votes have not been included in the current total, so it's unclear what Trump thinks this will accomplish. An additional, even more outrageous proposal, is to have their Republican allies in the state legislature use the doctrine to choose their own pro-Trump electors despite losing the popular vote.
This argument rests on an idea called “independent state legislature doctrine” discussed by then-Chief Justice William Rehnquist in the 2000 Supreme Court case Bush v. Gore. According to ProPublica’s Ian MacDougall, Rehnquist narrowly read the Constitution as giving state legislatures, rather than courts or election boards, “exclusive authority to run presidential elections.” As NBC News election law analyst Michael S. Kang wrote, the doctrine “is neither established nor persuasive legal theory,” and it clings to “a one-off reference to a concurrence in Bush v. Gore itself — joined by only three justices.” In fact, the Supreme Court disposed of this argument in Arizona State Legislature v. Arizona Independent Redistricting Commission, decided by the court in 2015, though Justices Brett Kavanaugh, Samuel Alito, Neil Gorsuch, and Clarence Thomas have signaled they agree with the doctrine.
This is how Trump has decided he will steal the election: with a rejected, long-shot legal argument fueled by Fox.