4 got it right. He already has the ultimate authority. Thomas Jefferson used it. He should announce the Trump slate of electors for all the contested states. The dems will have to object. He can then overrule their objection or go into the 2 hr session. When that ends without agreement between the houses, the Trump slate stands.
I believe if House and Senate disagree, the electoral slate certified during safe harbor period is the one that prevails.