WASHINGTON (AP) _ In a post-Perot post-mortem, experts on the politics of discontent contended on Tuesday that the two-party system is bound to give way over the next 10 years to a multi-party structure in America.

''We've found a level of discontent in American politics and American institutions that simply knows no parallel since the beginning of polling in the 1930s,'' said pollster Gordon S. Black, seeking to measure the public's appetite for trying something new. ''Over half the people are willing to bolt the party system.''

Analysts said future third-party movements are likely to grow from the ground up, electing local and state officials and members of Congress before trying to capture the White House. Ross Perot's supporters tried to elect him with no party at all.

''The American love affair with the two-party system is just about over,'' said John B. Anderson, a former Republican congressman from Illinois who bolted his party to run for president in 1980. After a strong start, he wound up with only 6.6 percent of the popular vote.

If a new party starts in 1996, ''it may take six years before they can elect a president,'' Anderson said, citing the history of the Republican Party. It was founded in 1854, six years before Abraham Lincoln came along to lead it into the White House.

Larry Harrington, a Democratic consultant who managed Al Gore's 1988 campaign for the presidential nomination, dissented from the view that the discontent of 1992 is likely to give rise to new political parties.

He said those backing Perot and supporting term limitation movements are inherently anti-politics and thus unlikely to coalesce politically.

They don't share a leader or an ideology, he said, and ''it is very difficult to govern under those circumstances.''

Joining at a Campaign magazine forum to evaluate the course of political discontent that the Perot movement tapped were Joan Vinson, Perot's Maryland coordinator; Black, who conducts polls for USA Today; Harrington and Joe Trippi, another Democratic consultant, and Lionel Kunst and Jim Coyne, leaders of organizations backing term limitation proposals that will be on the ballots of 15 states this fall.

Black said his polling suggested the willingness to elect a third-party president is far stronger than when Anderson ran.

Any new parties that evolve, the experts said, were likely to champion a variety of causes.

Most commonly foreseen was the development of a ''Green Party'' devoted to protecting the environment. Also envisioned were a party dedicated to preserving family values; a private enterprise party advocating that most government functions be contracted to private business, and a citizen- legislator reform party growing out of the term-limit movement.

Coyne said that movement already has become a ''third force'' in politics, gathering signatures from 3.5 million voters ''without the benefit of someone with a billion dollars paying for it.''

Trippi said the 800-number telephone technology that energized Jerry Brown's campaign for the Democratic presidential nomination and the Perot petition drives were changing the nature of politics.

When Anderson ran, he said, ''there wasn't the technology that allowed masses of people to respond in one second to something said on television.''

But he questioned whether a movement without a single leader can create a national party. Instead, ''it is going to start taking place in congressional races,'' he predicted.

Joan Vinson, who headed the Perot Committee in Maryland, said she senses a determination among Perot volunteers - estimated by Black to number over 200,000 at the time of Perot's withdrawal - to keep their movement alive.

''Something has started which will not go away,'' she said. ''There are many options open to us. A third party is certainly one of them.''

For the moment she wasn't ready to concede that Perot was irrevocably out of the race.

Noting his determination to continue the campaigns to place his name on all 50 ballots, she said Perot still could declare himself a candidate in October if he doesn't like the content of the campaigns conducted by President Bush and Bill Clinton.