The Maryland Politics Blog at the Washington Post says:
Sen. Allan H. Kittleman (R-Howard) parted ways with fellow Senate Republicans on Tuesday as they voted as a caucus to oppose a same-sex marriage bill pending in the Maryland General Assembly this year.The Gazette has more on Sen. Kittleman's plans during the session and his decision to step down as Republican Leader.
In an interview, Kittleman said he thought the caucus position was wrong and would announce his intentions in coming days.
Update: Sen. Kittleman has said he will support the bill to bring marriage equality to Maryland:
As a strong proponent of personal and economic liberty/freedom, I simply could not, in good conscience, vote against SB 116," Kittleman wrote in a explanation of his decision.