Washington area members of Congress and local officials staged an unusual display of regional harmony on Capitol Hill yesterday, vowing to replace political backbiting with cooperation when new leaders take office next month.

House members and local government leaders from the District, Maryland and Virginia came together for the first time in recent memory in a closed-door session that participants later described as positive and "tremendous." Rep. Constance A. Morella (R-Md.), who convened the session, said it demonstrates "a new breeze blowing through" local political circles.

Participants predicted that the unity displayed at the session will improve the prospects of the region, particularly the District, of getting money and legislative action from Congress. They also said that the absence of several controversial officeholders who were defeated at the polls last month will ease tensions within the region.

Audrey Moore (D), chairman of the Fairfax County Board of Supervisors, said there was "a tremendous response to the meeting, and a good tone among those there. We can't let the Potomac River become the Berlin Wall. I think we've got a good group of people who are willing to work together."

Among those attending were Virginia Rep. Frank R. Wolf (R) and Rep.-Elect James P. Moran Jr. (D), D.C. Mayor-Elect Sharon Pratt Dixon (D) and Del.-Elect Eleanor Holmes Norton (D), Montgomery County Executive Neal Potter (D), Prince George's County Executive Parris N. Glendening (D), Arlington County Board Chairman Albert C. Eisenberg (D) and Alexandria Vice Mayor Patricia S. Ticer (D).

Yesterday's meeting contrasted sharply with hostile public exchanges involving some of the area's outgoing public officials, including Rep. Stan Parris (R-Va.) and D.C. Mayor Marion Barry.

Parris frequently questioned the competence of the District government, and Barry accused the predominantly white suburbs of racially motivated antagonism against the majority-black District.

Several officials said that the absence of those two men will ease relations among local leaders.

"There is already a much different tone," Moran said recently. Barry and Parris "are two very visible politicians who in some ways exploited racism for personal political advantage. Both are out of the picture, and that changes the perspective."

Norton said the District's relationship with officials in surrounding jurisdictions "has changed already. {Dixon} made savings in the District budget a central part of her campaign, which has had a salutary effect. And this regional meeting would not have happened if Stan Parris were still here."

Yesterday's meeting was the second attempt to hold a regional summit since the election. An earlier session planned by Rep. Steny H. Hoyer (D-Md.) was canceled when a last-minute conflict arose on Capitol Hill.

A second regional summit has been scheduled for February, when leaders will discuss how to get more transportation money for the area.

Dixon said that the changes in the ranks of local officials afford an opportunity for the District to mend fences with its neighbors. "There's been an outpouring of goodwill, and this is our chance to leverage that goodwill," she said recently. "The opportunity is ripe."