(Bill O'Leary/WASHINGTON POST)

The event Wednesday in Chevy Chase will benefit Equality Maryland, which is also using the occasion to honor four other Democrats, all of whom are gearing up to run for governor in 2014.

“I cannot stress enough how important the next few months will be in achieving marriage equality in our state,” O’Malley says in an e-mail solicitation for the event, for which tickets start at $50. “We ... need your help to build a strong grassroots organization to pass this important legislation next year.”

O’Malley aide Rick Abbruzzese said the event is “the first of many” in which the governor will play a visible role trying to build support for same-sex marriage legislation.

“It’s not going to be news to anyone in that room that we have work to do,” Abbruzzese said.

O’Malley pledged to sign a same-sex marriage bill during this year’s legislative session if it reached his desk, but his advocacy was largely limited to private meetings with lawmakers. The bill narrowly passed the Senate but fell short in the House of Delegates.

The event also underscores the wide support for same-sex marriage among Democrats seeking to succeed O’Malley in Maryland in 2014.

All four of the party’s most frequently mentioned potential nominees are being honored, including: Attorney General Douglas F. Gansler, the first statewide elected official in Maryland to voice support for the issue; Lt. Gov. Anthony G. Brown, who played a more vocal role in this year’s debate than O’Malley; Comptroller Peter Franchot and Howard County Executive Ken Ulman.

Franchot is the only one not planning to attend, due to a prior out-of-state commitment, an aide said.

The host committee for the event reads like a who’s who of leading Montgomery County Democrats, including County Executive Isiah Leggett (D), and also includes some high-profile advocates of the legislation from other jurisdictions.