"I could very comfortably go down there (to Capitol Hill) for 20 years," Michael D. Barnes mused yesterday, savoring his election conquest of incumbent Rep. Newton I. Steers Jr. (R-Md.).

Barnes, the first Democrat elected to Congress from Montgomery County in 20 years, could contemplate a long tenure in the House because of his age and a Democratic voting edge of 2-to-1 in the 8th Congressional District.

"I'm only 35," Barnes said, adding that he could spend two decades in Congress and quit at an age where he could still look for a new challenge.

One of the stumbling blocks to Barnes' strategy, however, could be Steers, who said yesterday that he has not decided "if I'll take another crack at it in two years."

Steers, 61, recalled that during the campaign Barnes "put great store in the fact that a Democrat wins this seat every 20 years. But he should also realize that they last only one term." (The last Democrat to win the seat was John Foley, who served in the House from 1958 to 1960).

Barnes, who was victorious in his first try for elective office, plans to go to the Capitol today and meet with House Speaker Thomas P. (Tip) O'Neill, Jr. and discuss committee assignments and office space.

"I've got an 'in' with Tip," Barnes joked, explaining that the daughter of the speaker's administrative aide has worked as a baby sitter for Barnes and his wife.

Despite that tie, office location is a matter of the luck of the draw, said the administrative aide, Gary Hymel, whose daugher, Joy, has taken care of the Barnes' 3-year-old daughter, Dillon.

Barnes will have better luck on committee assignments, Hymel said. Barnes told Hymel on the telephone yesterday that he would like to serve on the International Relations and District committees.

"Both committees are wide open," Hymel said. If however, Barnes should want to serve on Ways and Means, which he has thought about, there would be competition, as only two spots on that prestigious committee are likely to be available to the 41 new House Democrats, Hymel said.

Barnes' strategy "all came together nicely in the last 10 days," his campaign manager, Keith Haller said yesterday. Reviewing the 4,921-vote margin, Haller said "we were right on target. We planned to come out of Silver Spring with a 7,500-vote lead, 1,400 more in Rockville, 500 in Chevy Chase, hold him even in Gaithersburg and lose Bethesda by no more than 500."

The final unofficial returns showed Barnes with 80,297 votes, or 51.5 percent, and Steers with 75,376 votes, or 48.5 percent.

Steers spent yesterday "licking my wounds," he said. After going through some mail at his congressional office, he took his staff to lunch and tried to console them.

He doesn't have any plans for next year "because I didn't expect to lose." In the meantime, he's going to take a few days off "and catch up on my reading. I've got quite a few back issues of Scientific American."

Barnes also is going on a vacation, to Bimini, which prompted Steers to decide to "go someplace besides the Bahamas. I've seen enough of him for a while."