Still if all 3 states fail to make a timely recount and fail to appoint their slate of Trump-Pence electors…then the presidential race will be thrown into the House where each State has one vote. Under Article II and the Twelfth Amendment, Trump has to carry a majority of state delegations (26 of 50). There is a separate quorum requirement: 2/3 of the States (34 of 50) must have one or more members present. Trump can probably meet this bar: 32 of the state delegations in the 115th Congress will have Republican majorities (albeit some are narrow majorities), and 11 other state delegations have 1 or more Republican members. So the Republicans should be able to reach a quorum of 34 States with one or more members present.
However, if all three 3 states fail to make a timely recount and fail to appoint their slate of Trump-Pence electors…then the vice presidential race will be thrown into the Senate. Under Article II and the Twelfth Amendment, Pence will need a majority of the “whole number” of senators. The Republicans have such a majority. But the Twelfth Amendment also has a quorum requirement: “two-thirds of the whole number of Senators.” [2/3 is 67 of 100 senators, assuming all elected Senators are alive and sworn during the proceedings to select a Vice President.] The Republicans cannot meet this bar, at least not absent Democratic participation. By absenting themselves, the Democrats can block the narrow Senate Republican majority from selecting Pence.