Joseph E. Preston is a step closer to realizing his 21-year-old dream of representing the Petersburg area in the General Assembly.

The attorney from Petersburg celebrated his 58th birthday by capturing the Democratic nomination for the 63rd House of Delegates District on Monday night, gaining a leg up in his quest to secure the seat recently vacated by new state Sen. Rosalyn R. Dance.

The next step for him is the special election Tuesday, Jan. 6.

With no Republican entering the race, Mr. Preston will have only one challenger, an independent, William H. “Mouse” Jones, 58, a well-known community activist and concert promoter in Petersburg.

Mr. Jones refused to participate in the Democratic Party’s nomination process because he felt it was unfair. He filed his final paperwork to enter the race close to the 5 p.m. Wednesday deadline.

Mr. Preston gained the party nod with a surprisingly easy victory over two rivals, Petersburg Mayor Brian A. Moore and Dinwiddie minister Larry D. Brown Sr.

The nomination was determined in a five-hour “firehouse primary,” a process that allows participants to vote by secret ballot.

The tally released after voting ended 8 p.m. Monday shows Mr. Preston won 536 votes or 52 percent of the 1,017 valid votes that were cast at the single voting place, Petersburg’s train station in Ward 4, which Mr. Moore represents on the Petersburg City Council.

Mr. Moore, who appeared to be the front-runner coming into the race, finished a distant second with 274 votes, or 27 percent. Mr. Brown received 217 votes, or 21 percent.

“I’m very happy,” Mr. Preston said after the vote as he offered thanks to the people who supported him in the rushed contest. The candidates worked during the Thanksgiving holiday to rally supporters.

“The people have spoken,” a disappointed Mr. Moore said, adding that he would “continue to work to move our city forward.”

Mr. Jones took hope from the tiny turnout. “He won with 500 votes in an area where at least 50,000 voters are registered. He’s supposed to be our leader with just 1 percent of the vote? I don’t think so.”

Mr. Preston has tried to win the seat before. In 1993, he lost his Democratic primary challenge to then-incumbent Delegate Jay DeBoer in the majority-black district that now includes Petersburg and parts of Hopewell and Chesterfield, Dinwiddie and Prince George counties.

Mr. Preston said he was encouraged to try again after Sen. Dance won the Democratic nomination for the 16th Senate District seat. The seat opened after Henry L. Marsh III resigned after 22 years to accept an appointment to the state Alcoholic Beverage Control Board. “My phone rang of the hook,” Mr. Preston said.

All three candidates were under pressure because the “firehouse primary” process was only announced Nov. 24, with a filing deadline of last Friday, Nov. 28.

The decision by the 63rd House District Democratic Committee to set up just one polling place at a site in Mr. Moore’s district did not sit well with the other potential candidates. One, Petersburg School Board member Atiba Muse, dropped out of the race, with criticism that the process was tilted in favor of Mr. Moore.

The single voting place definitely put Rev. Brown, pastor of Gravel Run Baptist Church in Dinwiddie, at a disadvantage because his supporters had drive up to 20 miles to vote.

The impact of the decision can be seen in the vote totals, which show little participation from voters outside Petersburg. For example, only seven Hopewell residents and 12 Prince George residents cast ballots. Only 73 Dinwiddie residents voted and just 114 Chesterfield residents cast ballots.

That compares with the 811 ballots from Petersburg residents, who essentially decided the primary winner.

Mr. Preston captured 448 of those 811 Petersburg votes, or 55 percent, to swamp Mr. Moore, who received 210, or 26 percent, of the votes cast by Petersburg residents. Rev. Brown received 153 votes from Petersburg, or 19 percent.

A native of Omaha, Neb., Mr. Preston, who turned 58 on Nov. 30, credited his three decades of community service in Petersburg for helping to generate the support.

“People know what I have done,” he said, citing his service on the boards of Legal Aid, the public library, Boy Scouts, YMCA and the court services unit of the Petersburg Juvenile and Domestic Relations District Court.

If he goes on to win the election — and as the Democratic nominee, he is considered the favorite — he pledged to be a “strong advocate for the needs of our district.”