A revolutionary Hatch Act bill that would allow civil servants to run for office, manage campaigns and solicit contributions on their own time was unanimously approved yesterday by a House committee.

The bill, if passed by Congress as its supporters predict and signed by the president, would have its greatest impact in the Washington metropolitan area, where 357,552 federal and postal workers form the largest concentration of federal workers in the nation.

Under the 48-year-old Hatch Act, federal employes have been barred from participating in most partisan political activities. The prohibition has shaped -- some say warped -- the local political picture for decades, leading to the creation of nonpartisan parties, shrinking the pool of political activists and prompting many government employes to work surreptitiously on behalf of presidential and congressional candidates.

Post Office and Civil Service Committee Chairman William D. Ford (D-Mich.) said an effort was being made to reach a "possible accommodation" with the administration before the bill is sent to the House floor. He said the measure has widespread support in the Senate and likely will be taken up there next spring.

Washington area politicians said yesterday that the proposed change could result in the creation of a cadre of highly motivated and knowledgeable activists, greatly strengthen the hand of government employe unions in campaigning for presidential candidates, and possibly inject a far more partisan flavor into suburban Washington politics.

"I can't think of a change that would have more dramatic impact potentially," said Keith Haller, a Maryland political consultant and pollster.

Michael D. Barnes, a Democratic former House member from Montgomery County, said the proposed change would have the greatest impact in congressional races because government workers hold strong views on the way government should be run.

"In the past there has been some informal participation in campaigns by federal employes, but I think this would change things dramatically," Barnes said. "I think the impact in the Washington area political arena would be very significant."

Albert C. Eisenberg, chairman of the Arlington County Board, agreed that a change in the Hatch Act would have important consequences in Northern Virginia politics, but questioned whether it would automatically unleash a torrent of new political activists.

"We must recognize that those who get charged up -- who want to get involved in politics, stuffing letters, working on the phone banks -- are a very small part of the population, even in an area as politically astute as this one," Eisenberg said.

In discussing yesterday's action by the House committee, Rep. Frank Horton (R-N.Y.) called it "an historic step," adding, "It is very seldom that all the Republicans and all the Democrats agree."

"Everybody is for this," said a spokesman for the House Democratic leadership, "but we're giving the ranking Republican time to check with the White House before setting a timetable."

House Republicans, including Minority Leader Robert H. Michel (Ill.), met with Constance J. Horner, director of the Office of Personnel Management, to "look into this idea of trying to look at the bill affirmatively, not negatively, not to look for problems," according to Michel.

Horner said the administration had reached no conclusion on the bill, but "we object to any rush to jettison four decades of bipartisan commitment to a nonpartisan civil service."

"I have waited 12 years for this," said Rep. William L. Clay (D-Mo.), sponsor of the legislation. Rep. Constance A. Morella (R-Md.) called it "the 1987 great compromise."

While freeing federal workers to participate in politics, the bill contains strict rules against on-the-job political activities by government workers and political coercion by government officials.

The bill specifically prohibits contributions to superiors or solicitations of government contractors, regulated industries and others seeking government favor. It bans the use of government money for political activities, and bars any political activity on the job -- including the wearing of campaign buttons.

Clay said "strengthened" provisions to protect employes from coercion will be enforced by the Office of the Special Counsel, which enforces the current act.

Bernard Demczuk, national political field director for the American Federation of Goverment Employes (AFGE), said that government workers could command "a much greater level of respect" if the bill is passed.

"We have been stepped on too long by the Congress and having the Hatch Act reformed not only gives us first-class citizenship but it gives us a political weapon to utilize in our own defense."

The Hatch Act has been a major irritant for leaders of the major public employe unions in seeking to assert greater influence in national politics.

Last February, the national presidents of the three largest federal and postal labor unions were ordered suspended from federal employment for 60 days for violating the Hatch Act, a punishment with little effect because all three leaders had been on leave without pay for more than 15 years.

The union presidents -- Morris Biller of the American Postal Workers Union, Kenneth T. Blaylock of the AFGE, and Vincent R. Sombrotto of the National Association of Letter Carriers -- called the action a "carefully orchestrated political attack" by the administration.

The bill approved yesterday would have a double-edged effect in the District of Columbia, home to the largest concentration of federal workers in the area, as well as most of the 41,000 D.C. government employes who also have been prohibited from engaging in political activities under the Hatch Act.

D.C. Council members and officials of Mayor Marion Barry's administration acknowledge that many city workers have routinely skirted the Hatch Act strictures to campaign for Barry, council members and for presidential candidates. In 1984, for example, many D.C. workers used their lunch hours and other time away from work to help campaign for Jesse L. Jackson's campaign for the Democratic presidential nomination.

"{D.C. employes} already are working in campaigns and at the polls," said council member John Ray (D-At large), who favors a change in the law. "But it's at a level that keeps a shield of protection. This {bill} would move away that last impediment."

The Clay bill is silent on the issue of D.C. government employes but a parallel effort by Del. Walter E. Fauntroy (D-D.C.) is under way to lift restrictions on political activities by city workers.

Council Chairman David A. Clarke and most other council members favor a change in the law to permit political activity by federal and D.C. workers, but many stress the need for safeguards to prevent the mayor and other city officials from coercing employes to campaign for them.

"I do think if you lifted Hatch Act restrictions -- as if they're listened to in the District -- there would be tremendous pressure on the 40,000 employes to work for the incumbent mayor, no matter who that is," said council member Carol Schwartz (At Large), the lone Republican on the council.

Barry has testified in support of exempting D.C. employes from Hatch Act restrictions, noting that the right to engage in partisan politics is granted to most Maryland government employes, all Virginia government employes and government employes in at least 11 other states. While acknowledging the need for strong safeguards against coercion, he denied yesterday that he would attempt to pressure city workers to campaign for him.

"I don't have to," he said. "They agree with me a lot. My problem is to put pressure on them not to campaign for me under the Hatch Act."

Over the past three decades, imposition of the Hatch Act has given Washington area local politics a distinct nonpartisan flavor, although more recently the trend has been toward greater identification with political parties.