The Alaska Republican, a frequent critic of the president who is often a swing vote, acknowledged the bill would harm Americans but backed it after winning carve outs for her state.
New provisions that benefit whaling captains and rural hospitals appear to be aimed at winning over Senator Lisa Murkowski, the Alaska Republican who had said the bill would hurt her state.
Senator Murkowski arriving to the U.S. Capitol in Washington earlier this month. For weeks she had openly voiced her displeasure with how several provisions in the legislation could impact Alaskans.
Republican leaders barely scaled a key procedural hurdle to bring up the bill, but Democrats delayed its consideration and it was unclear whether the G.O.P. had the votes to pass it.
G.O.P. leaders in the Senate are trying to quickly pass the legislation and send it to the House for final approval in time to meet the July 4 deadline that President Trump has set.