By Ian Simpson and Tom Ramstack
WASHINGTON (Reuters) - District of Columbia residents voted on Tuesday in a crowded Democratic mayoral primary, with the scandal-tarnished incumbent, Vincent Gray, facing a stiff challenge from a city councilor and ally of the previous mayor.
Polls show Muriel Bowser, who helped manage Adrian Fenty's successful 2006 mayoral campaign and later was elected to city council, in a tight race with Gray, who has presided over an economic boom in the U.S. capital.
Gray's re-election campaign has been dogged by questions stemming from the financing of his 2010 primary victory over Fenty, with three of his former officials having pled guilty to federal campaign financing charges.
The 71-year-old Gray has denied any wrongdoing, but many voters said the scandal had dulled their view of him.
"I want to get a new mayor," said Saundra Stephens, a former government worker who was headed to vote at a church in the southwestern part of the city.
Bowser has been endorsed by the Washington Post and enjoyed a funding advantage during the campaign, having raised $1.4 million to Gray's $1.2 million as of March 24, according to the District's Office of Campaign Finance.
Bowser had 30 percent of likely voters' support versus 27 percent for Gray in a Post poll released last week.
Although there are eight candidates in the Democratic primary, winning the race is seen as tantamount to taking the general election in a city that is heavily-Democratic and about 50-percent black.
Both Bowser and Gray are black, but Gray has stronger support in largely black wards, the Post survey showed.
It has been three weeks since Washington, D.C., businessman Jeffrey Thompson, a former government contractor, pleaded guilty to violating campaign finance laws.
Federal prosecutors had accused Thompson of aiding Gray through a "shadow campaign" that funneled more than $660,000 through friends and relatives to Gray's 2010 election effort.
Gray, a former head of the city's human services department, has denied anything illegal took place.
Some voters said they considered the scandal to be little more than a distraction from more important issues.
"We just need to improve our school system," said Chris Murray, a government worker. "I support Gray and I believe he has integrity."
Michael Fauntroy, an associate professor at Howard University and a political analyst, said the possibility that Gray could be indicted has made the primary too close to call and overshadowed other issues.
"But for this Thompson indictment we wouldn't be having this conversation, because everybody would be talking about what (Gray) was going to do in his next term," Fauntroy said.
Thompson's plea bargain was the latest in a long line of District scandals that include the 2008 conviction of a tax official for embezzling almost $50 million and Mayor Marion Barry's conviction on a drug charge in 1990.
Barry, now a city council member, endorsed Gray two weeks ago, calling him "a man of integrity."
The winner of the primary will face David Catania, an openly gay independent member of the city council and seen as the leading challenger in November.
(Editing by Scott Malone, Leslie Adler and Paul Simao)