The rebellious group of House Democrats leading the "dump Carter" movement announced yesterday they have lined up $200,000 to fund a crash campaign aimed at opening the Democratic presidential nomination to candidates other than Jimmy Carter and Edward M. Kennedy.

The three dozen House members working to expand the party's choice said they have formed a "committee for an Open Covention," which will lobby convention delegates and party leaders in the two weeks before the convention opens in New York.

Working with some $200,000 in pledges already rounded up by Arnold Picker, a California Democrat who started a "dump Carter" effort of his own earlier this month, the House Democrats plan to set up offices in Washington and New York to begin contacting delegates.

The House group, made up mainly of junior Democrats who have little influence or recognition beyond their own congressional districts, also began to line up backing from some senior party officials.

Govs. Hugh Carey of New York and Richard Lamm of Colorado both expressed support for the "open convention" idea, and suggested it will be a major topic among Democratic governors at a national governors' conference in Denver next week.

At least three promient Democratic senators -- Gaylord Nelson of Wisconsin, Daniel Patrick Moynihan of New York and Henry M. Jackson of Washington -- also called for the convention delegates to consider alternatives to Carter and Kennedy.

This came after a Philadelphia Democrat, S. Harrison (Sonny) Dogole, said Sunday he would form a separatate committee designed to make Jackson the Democratic nominee. Jackson declined either to embrace or reject Dogole's efforts on his behalf.

In another development, Vice President Mondale said he has no intention of becoming a candidate for the Democratic presidential nomination this year and will do everything he can to ensure Carter's reelection.

White House sources said Secretary of State Edmund S. Muskie planned to make a statement similar to Mondale's. But an official close to Muskie said the secretary has not ruled out accepting a nomination. "He is not the type to rule anything out," the official said.

Mondale sought to squelch an attempt to draft him in a frank letter to Rep. James L. Oberstar (D-Minn.).

"I have just learned of your statements over the weekend regarding proposals to change the Democratic convention rules and the possibility I might become an alternative candidate for the Democratic presidential nomination," Mondale said.

"I am not a cadidate for the Democratic presidential nomination this year, and I have no intention of becoming one," Mondale wrote. "President Carter has won a majority of the delegates fair and square, and I intend to do everything I can to ensure his renomination and relection."

It is still not clear whether any of these campaigns will be able to keep the nomination out of Carter's hands. In primaries and caucuses this spring, the president won the support of about 2,000 national delegates, some 300 more than he needs to win any convention floor vote, including the nomination.

The "open convention" advocates will have to convince a majority of the delegates to vote against a proposed party rule that would bind all delegates to vote for the presidential nominee they were originally pledged to support. Carter, with his control over a strong majority of the delegates, is urging his backers to vote in favor of that "binding" rule.

Kennedy, as Carter's only challenger right now, is working to defeat this rule. This has prompted the Carter campaign to charge that the "open convention" drive is really a shadow Kennedy effort.

The House members who announced the "open convention" committee yesterday, though, took pains to say that they were not supporting Kennedy or any particular candidate.

They also tried to duck the "dump Carter" label but in interviews, the upstart Democrats made it clear that they fear for their party and for themselves if Carter heads the Democratic ticket this fall.

Six House members -- Michael D. Barnes of Maryland, Jerome A. Ambro and Thomas J. Downey of New York, James Weaver of Oregon, and Norman D. Dicks and Al Swift of Washington -- called a press conference yesterday to announce formation of the "open convention" committee.

Barnes, a business-like, tweedy 36-year-old lawyer from Montgomery County, and Ambro, the gruff, scrappy 52-year-old ex-mayor of Huntington, Long Island, did most of the talking, and between the two of them they captured the conflicting strains of thought in the late-starting "open convention" drive.

Barnes, cautiously avoiding any harsh comment about Carter ("It is not our purpose to be derogatory . . ."), said the group's main interest was the nomination "process." He said he was motivated by "a responsibility to our party, a responsibility to our nation," and eschewed any concern for his personal reelection prospects.

Ambro, in contrast, conceded from the start that "this question of survival is finally honed, as Darwin tells us, in all of us." He said Democrats wanted to find a new nominee because President Carter" and they might not turn out to help other Democrats -- like the congressmen -- who have to share the ticket with Carter.

Established party leaders yesterday dismissed the Barnes group as "a bunch of ADA [Americans for Democratic Action] liberals and Kennedy supporters" with little real following. Asked about the "dump Carter" movement, House Majority Leader Jim Wright, for example, said, "I think it will fizzle out."

Wright said he doesn't expect Carter to pull down many Democratic congressmen. "Most members of Congress rise or fall on their own merits," he added.

Another senior House Democrat looked at the list of congressmen associated with the group and said, "I don't think this group could get a bill passed." The point was, then, how could they topple an incumbent president.

The group does include many of the youngest and most liberal members of Congress. Many of them have made their mark -- both in their home districts and in Congress -- by going against the gain. They are, for the most part, people never particularly comfortable with Carter.

There is not a single southern in the group. And the only person in it with anything approaching a leadership position is Rep. Don Edwards (D-Calif.), the fourth ranking Democrat on the House Judiciary Committee. Edward, first elected in 1962, is one of the most liberal members of the House and a former national chairman of the ADA, long the voice of the liberal establishment.

Many are members of the rambunctious Class of 1974, Democrats swept into office in the wake of the Watergate scandals. They think of themselves more as representatives of the "new politics" of the 1970s, which encompassed opposition to the Vietnam War and support of environmental issues, than of traditional Democratic Party constituencies.

Rep. Patricia Schroeder, of Colorado, first elected in 1972, won early attention in the Denver area by opposing the Winter Olympics in Colorado. Weaver of Oregon made a name for himself opposing the big timber interests in his state. Rep. Fortney H. (Pete) Stark (D-Calif.) first attracted attention in the San Francisco Bay area by erecting a peace symbol atop his bank.

"The group is generally the younger, more liberal Democrats who have come to the Hill since 1972," said Stark. "A lot of us have been getting together pretty regularly since my first term. They used to call us the Martin Point Gang. That's because a group of us got together one summer in a farm I rented on the Eastern shore of Maryland."

One fourth or more of the congressmen are active Kennedy supporters. Stark, Rep. John Conyers Jr. of Michigan and Rep. Richard M. Nolan of Minnesota, all participants in the group, were among the first five congressmen in the country to form a draft Kennedy committee more than a year ago.

Stark has been calling Carter delegates in California for weeks, trying to get them to switch to Kennedy -- with little success. "They keep telling me, 'Come on Stark, if we wanted Kennedy we'd have voted for him in the first place,' he said.

Barnes, who once worked on Muskie's Senate staff, went to Muskie and Rep. Morris K. Udall (D-Ariz) more than a year ago trying to persuade them to seek the Democratic nomination. Barnes, Schroeder, Ambro and Rep. Timothy E. Wirth of Colorado, and several other members were offically neutral in the Kennedy-Carter race.All face tough reelection fights.

"The common thread that holds us together is a feeling that the Democratic Party is in real trouble right now, and we need to do something to get it straightened out," said Weaver. "I think I'm in pretty good shape back home, but I have a swing district and a tide could always throw me out.

"As a group we don't rule the House," he added. "But I don't know who does at this point."