What tie can the vice president break?

If you mean, who would break a tie in an election for President, the answer is:

"If no candidate receives a majority of electoral votes, the House of Representatives elects the President from the 3 Presidential candidates who received the most electoral votes. Each State delegation has one vote. The Senate would elect the Vice President from the 2 Vice Presidential candidates with the most electoral votes. Each Senator would cast one vote for Vice President. If the House of Representatives fails to elect a President by Inauguration Day, the Vice-President Elect serves as acting President until the deadlock is resolved in the House."

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