Six weeks after losing a special election for a seat on the Arlington County Board, bank executive Monte Davis jumped back into the political fray yesterday, filing petitions to oppose Democratic board member Mary Margaret Whipple in November.

Renewing a theme from her unsuccessful campaign against Democrat James B. Hunter, Davis said in an interview that Arlington Democrats -- who control all 15 of the county's elected offices -- are shutting out dissenting opinions and not responding to residents' concerns. She said the current uproar in South Arlington over a county proposal to put minimum-security inmates, the homeless and drug and alcohol addicts in a 130-bed treatment center there reflects residents' dissatisfaction with county officials. Davis opposes the facility.

"This is one-party rule, with no checks and balances," said Davis, a county Planning Commission member. "I don't believe Arlington is above having a two-party system."

Whipple said yesterday that she and the four other board members have not decided whether to support the proposed treatment facility, which is scheduled to come before the board June 23.

More than 400 people attended a Planning Commission meeting Monday night to protest the proposal. County officials say the facility would include 70 beds for those jailed for offenses such as shoplifting, driving while intoxicated and possession of small amounts of drugs.

Davis, who as the Republican nominee received 45 percent of the vote against Hunter, will run against Whipple as an independent because the GOP filing deadline for the fall election was April 13.

Arlington County Republican Chairman Joan Haring said her party, which has no candidate in the November election, is expected to endorse Davis next week.

Davis said her petitions contained the signatures of more than 400 registered voters, well above the 125 required. Community leaders said some petitions were circulated at South Arlington neighborhood meetings at which residents vented their anger over the treatment facility, proposed for a site on South Four Mile Run Drive near Barcroft Park.

Whipple, who is seeking her third four-year term, said yesterday that she welcomes the competition, but Democratic activists said Davis might be making a mistake if she is planning to emphasize the uproar over the Barcroft proposal.

"It does seem surprising to me that someone may base a candidacy on an issue which . . . the board has not considered yet," said Whipple.

Davis said her campaign also will focus on other issues, such as what she said is a need to allocate more county funds to law enforcement and education. "This isn't a one-issue campaign," Davis said. "There's a lot more to it than that."