Hundreds of people rallied in Annapolis in March in support of tougher gun laws. (Marvin Joseph/The Washington Post)

A federal judge denied a pair of requests Tuesday to suspend key provisions in Maryland’s brand-new gun-control law, ruling that the plaintiffs had not made the case for the “extraordinary relief” they were seeking.

In denying the temporary restraining orders, U.S. District Court Judge Catherine C. Blake faulted gun-rights advocates for waiting until last week to challenge a law signed in May by Gov. Martin O’Malley (D). The new law, which includes strict licensing requirements for handguns and a ban on purchases of 45 types of assault rifles, took effect on Tuesday, hours before the court hearing.

“This could have been brought months ago and was not,” Blake told lawyers for the plaintiffs, who include gun owners, gun dealers and gun associations.

Blake indicated she would hear fuller arguments on the lawsuits in coming weeks, saying she had not made final decisions about the merits of the two cases.

Gun-rights advocates stressed their fight is not over.

“The fat lady hasn’t sung. She hasn’t even taken stage yet,” Shannon Alford, a lobbyist for the National Rifle Association in Maryland, said outside the Baltimore courtroom. While the NRA is not a party to either lawsuit, it has been providing support “in every way we can,” Alford said.

The first of the lawsuits argues that Maryland’s ban on specified assault rifles and detachable magazines with more than 10 rounds violates citizens’ right to protect their homes under the 2nd Amendment.

Matthew J. Fader, a lawyer for the state, countered that the General Assembly prohibited purchases of “a particularly dangerous class of weapons suited for military assaults” and was not trying to impede efforts at self-defense.

The second lawsuit argues that expected delays in processing new licensing requirements — including fingerprinting of gun buyers — amount to a de facto ban on handgun sales.

Fader said it was “pure speculation” that there would be delays caused by the new requirements. As of Tuesday morning, he said, a Web site was operating for people interested in beginning the licensing process.

Maryland’s new law came in response to the December shootings in Newtown, Conn.