Montgomery County Executive Sidney Kramer picked up an important endorsement yesterday from the county's firefighters as his write-in campaign for reelection showed the first signs of political vitality.

Kramer, who rocked county politics by reentering the executive race as a write-in after Neal Potter's surprising victory in the Democratic primary, was backed by groups representing 1,000 firefighters. They promised both money and campaign workers.

Kramer had been endorsed by virtually all labor groups during the primary. Yesterday's announcement was important as a signal that his against-all-odds bid is keeping at least some traditionally Democratic groups from supporting Potter, the party's nominee.

The unions representing county employees and teachers said yesterday they will stick with Potter. The Republican candidate on the Nov. 6 ballot is Albert Ceccone.

Kramer joined with officers of the Montgomery County Career Firefighters Association and the Career Fire Rescue Officers Association for a morning news conference at the newly opened headquarters of Citizens to Write-In Sid Kramer.

The headquarters, in a cavernous former car dealership in Rockville, bustled with the work of dozens of volunteers -- stuffing "Dear Friend" letters into hand-addressed envelopes, hammering lawn signs to stakes and painting placards.

The group, formed two weeks ago, has started to distribute 5,000 bumper stickers proclaiming "Save our County! Write in Sid Kramer." Lawn signs bearing the same message are appearing throughout the county. And the committee has sent a special mailing to voters who have applied for absentee ballots.

"No career politicians here," Kramer said, striking the theme of the write-in effort as the grass-roots work of unpaid volunteers "not calloused by past campaigns." He acknowledged this second campaign contrasts sharply with his primary bid, which raised more than $280,000 and relied on paid office workers and political consultants.

Potter said he is "not much" worried by the activity in the Kramer campaign.

He noted that in the primary, Kramer had most of the endorsements and most of the money but still came up short. He derided the appearance of lawn signs, arguing that most have been placed illegally in public rights of way.

The write-in campaign puts the Potter camp in a bit of a bind -- how to officially deny Kramer status as a candidate without appearing to be complacent about the election. Democratic Party officials said support for Potter remains solid, with only one or two of the county's 300 precinct officials defecting to Kramer.

It is unclear who is paying the bill of the citizen group, which has been able to afford, among other things, a $1,000-a-month lease for the campaign headquarters. The group does not have to file a campaign finance report until Oct. 26.

Fran Abrams, chairman of the group, said the group hopes to raise $50,000. She said she didn't know how much money has been raised so far. Bills are being paid by various people who hope to be reimbursed, and some businesses, such as an advertising agency, have agreed to run a tab, she said.

Kramer, a self-made millionaire, said he has not contributed any money to the campaign and that there are still bills outstanding from his failed primary effort. He said if there is money left over, he would be glad to contribute it to the citizen group.

"I have not been asked for any contributions. If they ask me for it, I'll consider it but they have not asked," Kramer said.

Abrams and other Kramer supporters have described the group as a spontaneous outpouring of public support, which managed to cajole a reluctant Kramer into a write-in effort. Potter campaign supporters say that Kramer and some of the people he appointed to government positions are behind the effort.

According to some in the business community, Kramer has called on them for support.

Several business groups that endorsed Kramer in the primary but have taken a wait-and-see attitude about his write-in bid are set to meet this week to decide their position on the race.

Thomas C. Miller, president of the Bethesda-Chevy Chase Chamber of Commerce, said it is a dilemma for the business community because Kramer, "a conventional person" who has had their support, is doing something so "unconventional."