What role does the president play in a bill becoming a la

the president has the power to pass or veto the law.

A bill becomes a law when signed by the president. If the president vetoes a bill, Congress can override the veto by a two-thirds vote of both houses. There are many reasons for a president to reject legislation. For example, although the president may be supportive of the bill's main purpose, he may decide that it contains unacceptable riders.