The move was not surprising. Senate rules allow opponents to halt debate for a day to prepare amendments and sharpen their arguments.
Senate President Thomas V. Mike Miller said from the rostrum Wednesday that he still believes the votes are there to pass the measure. "I don't anticipate a single vote has changed," Miller said.
Senate Republican whip Sen. Edward Reilly of Anne Arundel County requested the delay. He was supported by Sen. C. Anthony Muse, a Prince George's County Democrat. Both lawmakers said they will offer amendments to the bill.
Last year the Senate passed a similar bill 25 to 21, with one member not voting because she was out of the chamber.
Debate is expected Thursday morning — and a final vote is expected either Thursday evening or Friday morning. Supporters have said they have the votes to stop a filibuster.
The House of Delegates narrowly passed the bill, which would legalize same-sex marriage in Maryland, Friday night. If the Senate approves the measure, both sides expect the legislation to be petitioned to referendum on November's ballot.