After attending a committee hearing one day last week, D.C. Council member Jim Nathanson (D-Ward 3) emerged from the council chamber to chat briefly with the last person who testified.

The man who shook hands and exchanged a few cordial words with Nathanson was Mark L. Plotkin, the Northwest Washington community activist who lost to Nathanson in last fall's Democratic primary by a mere 347 votes.

In Ward 3, it seems, the candidates involved in last summer's tight four-way race for the council seat vacated by the retiring Polly Shackleton have made their peace.

But for council member Harry L. Thomas (D-Ward 5), freshman year has been a different story. Although he bested his opponents -- including incumbent William R. Spaulding -- by more than twice the margins that Nathanson enjoyed in Ward 3, the election-year battle still rages.

"It's the craziest ward you've ever seen in your life," Thomas said recently. "And it's all sour grapes."

Both Nathanson and Thomas scored unexpected victories last year, and their election success brought two newcomers to the District Council at once, an unusual turnover for the 12-year-old legislative body.

Both wards are considered important political plums for anyone seeking citywide office -- Ward 3 because of its traditionally high voter turnout, and Ward 5 because its residents represent the backbone of middle-income black Washington.

Community activists in the two wards, asked to grade their new council members' first year in office, offer remarkably different opinions on how well Thomas and Nathanson are faring.

"He's hard working; he knows the issues and is reasonably accessible," Garth Beaver, 82, a member of the Wisconsin Avenue Corridor committee, said of Nathanson. Beaver was a Plotkin supporter last year. Nathanson "does a lot, and he doesn't make too much of a fuss about it either."

On the other side of town, the same question posed to Fort Lincoln activist Bob King, who ran twice for the council seat, garnered this response: "If I were asked to give {Thomas} his worst grade, it would be in trying to bring the leadership together in Ward 5. That role is equally as important as him working as a legislator."

What has been described as Thomas' continuing disaffection with people who did not support him is "a very emotional and turbulent situation" that is bound to affect his performance as the community's representative downtown, said former Spaulding supporter Douglas Daiss.

Nathanson, a low-key 54-year-old Harvard graduate and former public schoolteacher, is not that much different from Thomas when it comes to his community activist credentials. Each has risen through his ward organization and has been active in other election campaigns. "It's still a blood feud out there, and it is accelerating at an alarming rate."

-- Ward 5 resident Douglas Daiss

Unlike other council members, however, neither their rose to the council level by way of the school board or through connections established during the push for home rule or the civil rights movement.

But the similarity quickly ends. The contrast between Nathanson and Thomas as elected officials is as marked as the contrast between their wards. Thomas' is a collection of solidly middle-class black residents in upper Northeast, and Nathanson's is a largely white district in Northwest Washington, west of Rock Creek, where some of the city's most affluent residents live.

While Ward 3 community activists are battling against overdevelopment along Wisconsin Avenue, Ward 5 activists plead for more development along the New York Avenue corridor and other commercial centers of their ward.

During the election, Nathanson was endorsed by Shackleton, while Thomas ran against Spaulding and three others in a bitter feud that carried over into the general election. A key ingredient in Thomas' victory was his politically active wife, Romaine Thomas, a popular member of the D.C. Democratic State Committee.

Nathanson has introduced legislation and raised his neighborhood profile to a citywide one, calling for Fire Chief Theodore R. Coleman's resignation in the wake of problems with the D.C. ambulance service.

"Nobody ever suggested to me I should go slow," he said.

Thomas, who is usually silent during council meetings and committee hearings, is quick to cosponsor bills but does not feel that taking the lead on legislation is the main feature of his job.

"They wouldn't give a damn whether I passed one piece of legislation," Thomas said of his constituents. "All they want to know is that they have somebody down here.

"What good is it for me to be passing some legislation -- some of it as crazy as hell?" said Thomas. "Let's try to solve the problems of the city without a lot of grandstanding."

In Ward 5, however, the problems of the city take a back seat to the friction existing within a political structure that has been splintered for years, according to residents.

"It's still a blood feud out here, and it is accelerating at an alarming rate," said Daiss. Community meetings with Thomas present, Daiss said, have been marked by "name calling, screaming and hollering" among participants.

And Thomas does not back away from the battle.

This month, the council member wrote D.C. Democratic State Committee Chairman James M. Christian in response to a complaint that was lodged against Thomas by Robert I. Artisst, a perennial candidate for the Ward 5 council seat who finished behind Thomas and Spaulding in last September's primary.

In the two-page letter, Thomas criticized the "vigorous and antiparty actions of the likes of Mr. Artisst who bolted the party and supported my general election opponent," independent candidate Sharon Turner-Jackson.

Thomas does have his supporters. Joslyn Williams, the president of the Metropolitan Washington Council AFL-CIO, is happy with Thomas' prolabor stance and has called the council member "conscientious and sensitive."

The Ward 5 turmoil, Williams said, is to be expected in an area where a consensus has seldom existed. "It would be difficult to expect that after 12 years of internecine warfare there would be peace after a few months," he said. "It's going to be up to Harry Thomas as the incumbent now to try doubly hard to bring everyone under his umbrella and rally around him for the benefit of that ward."

Nathanson's political challenge, on the other hand, lies in representing an area of the city that showed its disenchantment with Mayor Marion Barry by overwhelmingly supporting his general election opponent, council member Carol Schwartz (R-At Large), who represented the ward as a school board member for eight years before her 1985 election to the council.

"The mayor appreciates the politics of Ward 3," Nathanson said diplomatically.

But Nathanson, in challenging Coleman and voting consistently in favor of a controversial public law school proposal that Barry opposes, is free to stand apart from the Barry administration in ways that Thomas, who received Barry's endorsement, cannot.

Just six months into their four-year terms, it is too soon to say whether Thomas and Nathanson will be successful in building their constituencies while accumulating some clout in the District Building, observers agree.

It appears that Thomas has the tougher row to hoe. But, Joslyn Williams added, "One could say with tongue in cheek that Democrats in Ward 5 would not know how to react if there were real peace out there."