An Upper East Side special election to fill an open Assembly seat could give Manhattan Republicans their first Albany-bound representative in years.

Seeking to end the GOP’s dry streak is Gregory Camp, formerly an investment banker, prosecutor, and deputy director of criminal justice for New York State.

He is running against Micah Kellner to replace Alexander “Pete” Grannis, who sat on the Assembly for 33 years before stepping down to become commissioner of the New York State Department of Environmental Conservation.

Mr. Camp, 45, supports women’s right to legalized abortion and gay marriage, and is opposed to the death penalty. He has bachelor’s, law, and business degrees from Yale University. He lives on East 69th Street between Second and Third avenues, with his girlfriend, Sonia Ossorio, president of the National Organization for Women in New York City, and his son and daughter from a marriage that ended in divorce.

Mr. Kellner, 28, a Democrat, is a former aide to Comptroller William Thompson Jr., Rep. Carolyn Maloney, and City Council Member Inez Dickens. He graduated from New York University in 2001 with a bachelor of fine arts in

film, television, and radio. He has won widespread support from Democratic officials in the city, including Speaker Christine Quinn and the president of Manhattan, Scott Stringer. Mr. Kellner, who says he is bisexual, said two New York gay Democratic clubs are backing him.

Democrats outnumber Republican voters in the district by nearly three to one, according to 2007 voter registration figures from the New York State Board of Elections. There are 74,307 registered voters in the district, which includes the eastern portion of the Upper East Side, Yorkville, and Roosevelt Island. Between 5,000 and 10,000 voters are expected to head to the polls for the special election June 5.

Most recently, Mr. Kellner was a community liaison representing Mr. Thompson on the Upper East and Upper West sides. He said his work with community boards and local residents on issues as varied as efforts to renovate a dog run and to install an elevator in a subway stop have steeped him in matters of local importance. Mr. Kellner has limited mobility in his right hand and right leg from cerebral palsy, and said he has worked to improve building and transportation accessibility for the disabled.

“I’ve never met Mr. Camp,” Mr. Kellner said earlier this week between sips of a Vanilla Americano at an Upper East Side Starbucks after a round of early-morning politicking on York Avenue and East 86th Street. “Where has he been in this community?”

Mr. Camp takes issue with Mr. Kellner’s characterization of him as a newcomer to the district. He said he has represented the county as an assistant district attorney under District Attorney Robert Morgenthau, and all of New York in his criminal justice position with the state. Some local issues may be somewhat new to him, but he is learning quickly, he said.

“I’ve been living in the district for 17 years. I’ve been raising kids in the district for 15,” he said. “I’ve been so engaged with the issues in this community on a personal level.”

Both candidates oppose plans to construct a waste transfer station on East 91st Street, but differ in their stance on congestion pricing. Mr. Camp supports Mr. Bloomberg’s proposal to charge drivers a fee to use the city’s most congested streets during peak hours. Mr. Kellner said he approves of “the concept,” but is not backing Mr. Bloomberg’s plan.

A political consultant, Joseph Mercurio, predicted Mr. Kellner would win the race. He said Mr. Camp may be cut from a similar political cloth as the popular mayor, but warned that his message will never reach voters.

“As soon as they hear the word ‘Republican’ they are going to write a script about him that relates more to Bush and the war,” he said. “Democrats are much more entrenched now.”