The Social Security Fairness Act is now in the hands of the Senate. Here's what could happen next.

Efforts to get the Senate to vote on a bill to expand Social Security benefits are intensifying, as the House-passed Social Security Fairness Act enjoys rare bipartisan support but has only a short window of time — six weeks — to be passed.

"We're guardedly optimistic," Shannon Benton executive director of The Senior Citizens League, or TSCL, an advocacy group devoted to protecting retirement benefits, said. "There is so much momentum, if it doesn't get passed now, a lot of people will lose hope."

Decades in the making, the legislation would eliminate a provision that reduces Social Security payments to some retirees who also collect a pension from jobs that aren't covered by the retirement program, such as state and federal workers including teachers, police officers and U.S. postal workers. It would also end a second provision that reduces Social Security benefits for those workers' surviving spouses and family members.