Esther P. Gelman, who hopes to use her 16 years in Montgomery County politics as a springboard to Congress, plans to celebrate her 55th birthday Saturday in election-year style, with a campaign fund-raiser and picnic.

Few other Montgomery Democrats have woven their private and public lives together as Gelman has.

The longtime County Council member believes her years of cultivating an eclectic set of interest groups will pay off in the party primary election this fall.

Gelman already is cashing in on her longstanding alliance with the county's development industry, reaping large contributions from executives of Montgomery's most prominent builders, including Tower Construction, Berger-Berman, Aldre Inc. and Charles E. Smith Co.

Less visible organizations also have endorsed her candidacy. The Gay-Lesbian Democratic Club of Montgomery County, a dozen fire and rescue squad chiefs, even the International Longshoremen's Association, recently have announced their support of Gelman.

Support from such diverse groups is testament both to the power Gelman has wielded on the county planning board and council and her own personal brand of politics, which has won her many allies but also caused deep schisms in the Democratic Party over the years.

Gelman, a Baltimore native who was raised in Denver, cut her political teeth on neighborhood zoning battles and has never forgotten the lessons of those earlier wars.

Unafraid to tangle with other political leaders in the county, most notably County Executive Charles W. Gilchrist, she has shown a knack for capitalizing on issues guaranteed to produce headlines.

Often, those battles have generated more heat than light, such as the costly investigations of Gilchrist's liquor department in the late 1970s and, more recently, the executive's economic development director.

In both cases, a majority of the County Council, led by Gelman and David L. Scull, pressed for the investigations. But those and other probes produced nothing that permanently damaged the Gilchrist administration.

Many Democrats believe the factionalism that has haunted the council for the past eight years is Gelman's major political liability, one she is trying hard to overcome by toning down her once-harsh rhetoric and restoring contact with other wings of the party.

Meanwhle, she is campaigning on her own considerable record of achievement in Montgomery and her work on such issues as care of battered women and the elderly, smoking bans in public places and collective bargaining rights for county government employes.

The energetic Gelman served as the first female president of the Maryland Association of Counties and its first presiding officer from Montgomery County.