Maryland Gov. Martin O'Malley, left, performs back to back with his fiddle player Jim Eagan as O'Malley's March plays an engagement last summer at Fort McHenry in Baltimore. (Bill O'Leary/The Washington Post)

The governor, decked out in a black T-shirt and black cargo pants, seemed more relaxed on stage than any time in recent memory. But the reemergence of his Celtic rock band was not altogether free of reminders of his elected office.

Fans of O’Malley’s March were greeted on West Street by several protesters whose signs registered their opposition to a possible casino in Prince George’s County. Maryland lawmakers could vote to authorize one during a special session that O’Malley has said he plans to call the week of July 9.

Inside the venue, Jared Denhard, who plays harp, trombone and other instruments, wore one of the “Dignity” buttons that supporters of O’Malley’s successful same-sex marriage legislation sported during this year’s legislative session.

And O’Malley told the audience about a visit in March to the White House — where O’Malley’s March provided entertainment as part of an extended St. Patrick’s Day celebration in honor of Irish Prime Minister Edna Kenny.

“They were so glad to have us, they told us three songs or 15 minutes, whichever comes first,” O’Malley said.

Monday night’s concert to a near-capacity audience comes during a relatively busy stretch for the semi-retired, seven-member band, which curtailed its public appearances during the run-up to O’Malley’s first bid for governor in 2006. Most of O’Malley’s advisers have long since shed concerns about his side career detracting from his gravitas as governor.

The set list at Rams Head on Monday ranged from ballads to rollicking Irish anthems, with several showcasing the musical talents of other members, including a fiddle player and accordionist.

It featured several songs penned by O’Malley back in the band’s heyday, when he was a Baltimore council member and mayor, including “Wait for Me,” “Streets of Baltimore” and “Battle of Baltimore.” He said the band plans to perform the latter two next month when it is booked to play with the Baltimore Symphony Orchestra as part of Maryland’s War of 1812 bicentennial commemoration.

A wide-ranging list of covers filled out Monday’s show, some with a Memorial Day theme and several on which on which O’Malley traded his emerald green acoustic guitar for a six-string banjo, which he told the audience is his “new toy.”

By the time the two-hour concert concluded with stepped-up version of Shane MacGowan’s “Streams of Whiskey,” the casino protesters outside were long gone. And it’s a safe bet a special session on gambling wasn’t foremost on the governor’s mind.