The Maryland State Senate passed same-sex marriage by a 25-22 vote Thursday night.
The passage of the bill comes less than a week after the .
The bill now goes to Gov. Martin O'Malley for his signature.
The law, which goes into effect Jan. 1, is expected to face a referendum challenge and could end up on the November ballot along with the bill that grants in-state tuition rates to some children of illegal immigrants.
All of Montgomery County's eight senators voted yes on the bill.