Rep. Constance A. Morella (R-Md.) announced yesterday that she will seek reelection next year, promising to continue as an "independent voice" for Montgomery County and displaying a calm assurance that her record will more than match that of any challenger the Democrats offer.

The popular first-term Republican declared her candidacy for reelection to the 8th District congressional seat to the applause of a small group of friends and supporters at a Bethesda news conference.

"My record is one of independence, judging each issue on its merits," Morella said. "My energy and resources have been balanced between matters of international importance and the concerns of the people in my district. Our future depends on the prosperity we promote at home and the peace we preserve in the world."

She identified reduction of the budget deficit and arms control as her major priorities, but, above all, pledged to work hard for "a unique constitutency that must have a strong advocate in Congress."

Morella is generally viewed as a formidable opponent, possessed of a winning campaign style and espousing a liberal-to-moderate Republicanism that plays well in the heavily Democratic district, which spans the southern half of the county from the D.C. border to Gaithersburg.

She also has not stopped campaigning since her upset victory last year over Democratic state Sen. Stewart Bainum Jr. to succeed Michael D. Barnes. She made the rounds of Metro stations the day after that victory to thank voters, has made constituent service a hallmark of her office and has spent considerable time at county events.

Her campaign office has remained open and, almost a year before the general election, has raised $185,000, her finance chairman said yesterday.

With about a month remaining before the filing deadline for the March primary, three Democrats have emerged as possible candidates:

Maryland Del. Peter Franchot is set to announce his candidacy on Saturday while County Council President Rose Crenca, favored by the county's key Democratic leaders, has kept people guessing about her plans. Crenca said yesterday she might make her plans known as early as today, but sources close to Crenca said she was leaning against running. Allan J. Lichtman, an American University history professor, also is considering running but is waiting to learn Crenca's decision.

Morella, who taught school in Montgomery County for 20 years while rearing nine children, also served in the Maryland state legislature for eight years.