Henry Bain, who until last week was the only Democratic candidate for Montgomery County executive challenging incumbent Sidney Kramer, ended his candidacy last night by throwing his support to veteran council member Neal Potter.

"I will walk out of here tonight as a volunteer in the Neal Potter county executive campaign," Bain told a group of 75 civic leaders and Democratic activists he called together to gauge support for Potter.

Bain quit his job as legislative aide to the County Council to announce May 29 that he would challenge Kramer because he believes Kramer's policies caused overdevelopment and fiscal problems. Potter, a council member for 20 years, entered the race just hours before last Monday's deadline. Bain said it made no sense for him and Potter to stay in the Sept. 11 Democratic primary because they stand for the same things.

Bain acknowledeged that Potter was better known, but he said he wanted proof that Potter could launch a viable campaign. Bain said last night's meeting at the Twinbrook Library in Rockville -- in which officials including county State's Attorney Andrew L. Sonner pledged to help Potter and residents stepped forward with checks of $25 and $100 -- convinced him.

The winner of the Democratic primary will face Republican Albert Ceccone in the Nov. 6 general election.