In a situation outlined in the 12th amendment where
" and if no person have such majority, then from the persons having the highest numbers not exceeding three on the list of those voted for as President, the House of Representatives shall choose immediately, by ballot, the President."
Is the representation from each state compelled to make a selection from the top 3 ? Can they abstain from voting and what are the legal consequences of doing so ? Also if they can abstain from voting for President would that block them from being able to vote for Vice President ?