If the VP spot is vacant, the president selects a new VP who must then be confirmed by the House and Senate; per the 25th amendment:
Whenever there is a vacancy in the office of the Vice President, the President shall nominate a Vice President who shall take office upon confirmation by a majority vote of both Houses of Congress.
Hmmm, simple majority vote. Interesting. So if we somehow got a Democratic house with a Trump presidency, they could just refuse to confirm any VP at all, which would make the speaker of the House 2nd in line for the presidency.
If the VP spot is vacant, the president selects a new VP who must then be confirmed by the House and Senate; per the 25th amendment:
Hmmm, simple majority vote. Interesting. So if we somehow got a Democratic house with a Trump presidency, they could just refuse to confirm any VP at all, which would make the speaker of the House 2nd in line for the presidency.