5. Bend the last guardrail: the U.S. Congress
Should a legislature claim the power to pick electors, that decision will be resisted in states with a Democratic governor—right now, those states include Michigan, Wisconsin, Pennsylvania, and North Carolina. The likely outcome of such a legislative power grab is that the governor, adhering to the popular vote results and the decision of state election officials, would appoint his or her own slate of electors, leaving it to Congress to sort out the dispute.
The process for choosing among competing slates of electors is complex, but the bottom line is that if both houses of Congress are controlled by the same party, that party’s electors will almost surely prevail. In this sense, the 2022 midterms could have a decisive impact on an electoral vote dispute. Right now, Democrats have only a slim House majority; the combination of traditional midterm losses for the White House and the likely effect of redistricting—Democrats had a disastrous election on the state legislative level— means Democrats are in real danger of losing the House. If they cannot take the Senate by 2024, that could mean that a rogue Republican state legislature can be confident that its decision will win congressional approval.