The President may veto a Bill passed by Congress by returning it unsigned and with objections within 10 days. The Bill is also considered vetoed if Congress adjourns within that 10 day window thereby preventing the Bill's return.

When the President vetoes a Bill, the Bill can only become a law if passed by two-thirds of the House of Representatives and two-thirds of the Senate.

The wording of your question is non-standard, because the Bill does not become a law until either the President: signs and returns it; or allows 10 days to pass. Once a Bill is a law, there is no more veto right.

See Article 1, Section 7, Clause 2:

Every Bill which shall have passed the House of Representatives and the Senate, shall, before it become a Law, be presented to the President of the United States; If he approve he shall sign it, but if not he shall return it, with his Objections to that House in which it shall have originated, who shall enter the Objections at large on their Journal, and proceed to reconsider it. If after such Reconsideration two thirds of that House shall agree to pass the Bill, it shall be sent, together with the Objections, to the other House, by which it shall likewise be reconsidered, and if approved by two thirds of that House, it shall become a Law. But in all such Cases the Votes of both Houses shall be determined by yeas and Nays, and the Names of the Persons voting for and against the Bill shall be entered on the Journal of each House respectively. If any Bill shall not be returned by the President within ten Days (Sundays excepted) after it shall have been presented to him, the Same shall be a Law, in like Manner as if he had signed it, unless the Congress by their Adjournment prevent its Return, in which Case it shall not be a Law.

The President has the power to veto a Bill passed by Congress by returning it unsigned and with objections within 10 days. The Bill is also considered vetoed if Congress adjourns within that 10 day window thereby preventing the Bill's return.

When the President vetoes a Bill, the Bill can only become a law if passed by two-thirds of the House of Representatives and two-thirds of the Senate.

The wording of your question is non-standard, because the Bill does not become a law until either the President: signs and returns it; or allows 10 days to pass. Once a Bill is a law, there is no more power to veto.

See Article 1, Section 7, Clause 2:

Every Bill which shall have passed the House of Representatives and the Senate, shall, before it become a Law, be presented to the President of the United States; If he approve he shall sign it, but if not he shall return it, with his Objections to that House in which it shall have originated, who shall enter the Objections at large on their Journal, and proceed to reconsider it. If after such Reconsideration two thirds of that House shall agree to pass the Bill, it shall be sent, together with the Objections, to the other House, by which it shall likewise be reconsidered, and if approved by two thirds of that House, it shall become a Law. But in all such Cases the Votes of both Houses shall be determined by yeas and Nays, and the Names of the Persons voting for and against the Bill shall be entered on the Journal of each House respectively. If any Bill shall not be returned by the President within ten Days (Sundays excepted) after it shall have been presented to him, the Same shall be a Law, in like Manner as if he had signed it, unless the Congress by their Adjournment prevent its Return, in which Case it shall not be a Law.