The Hawaii Senate on Tuesday is expected to give its final approval to a gay marriage bill, the last step for lawmakers before sending the measure to Democratic Governor Neil Abercrombie, who has said he will sign the bill as amended in the House.

The Senate overwhelmingly approved the measure 20-4 with one lawmaker excused, but changes made to the bill during a contentious House debate call for a return trip to the Senate.

Senator Clayton Hee, chair of the Senate's judiciary committee and the bill's champion in the Senate, said he expects the bill will face little opposition in the chamber and predicted a 21-4 vote.

Opponents looked to the House as their best chance to derail the bill. But only a couple of amendments out of dozens introduced received enough support during committee or floor debate to clear the chamber. The changes slightly expand religious exemptions.

If the measure becomes law, Hawaii would become the 16th state to allow gay couples to marry, joining recent entrants New Jersey and Illinois, where a bill awaits Governor Pat Quinn's signature.

(Related: Mark Kirk congratulates Illinois on passage of gay marriage bill.)