Jesse Jackson wades in. After fading from public view, Jesse Jackson has reentered the lists in defense of liberalism. Will it help Dukakis? (Debate analysis Monday.)

Jesse Jackson has rumbled back onto the 1988 campaign trail - defending liberalism and Michael Dukakis. Stung by George Bush's attacks on Dukakis liberalism, the Rev. Mr. Jackson has rallied to the governor's defense in recent days. He charges that liberalism is under siege. An entire generation of young Americans are being taught that to ``to grow up liberal is to be dirty, inadequate, un-American, subversive,'' he says. ``There is something dangerous about that.''

That sort of blunt talk from Jackson delights liberals, and may fire them up to vote for Dukakis on Nov. 8. But for Democrats, the ``L-word'' remains touchy. They know that in a year when most Americans shun the liberal label, the ``L-word'' that Democrats most dread is ``loser.''

Jackson's latest defense of liberalism came before a large audience at a luncheon sponsored by the Hollywood Radio and Television Society in Beverly Hills.

Heaping scorn on the Republican ticket, Jackson reminded the broadcasters that liberal political and social victories in the past have marked major turning points in America's history.

It was a liberal victory when the United States Supreme Court dropped its ``separate but equal'' doctrine in favor of ``equal justice under the law,'' he said.

It was a liberal victory in 1947 when the military was desegregated by order of President Truman.

It was a liberal victory when Jackie Robinson began to play for the Brooklyn Dodgers.

It was a victory when schools in Little Rock, Ark., were integrated, when blacks won the right to vote, when the poll tax was abolished, when open housing became law, and when all Americans won the right to use the same public restaurants, restrooms, and public parks, Jackson observed.

Jackson's relations with Governor Dukakis cooled after the Democratic convention, where the two men appeared to have reached an amicable accord on the black minister's role in Mr. Dukakis's campaign. Jackson later complained that Dukakis was not living up to the agreement. Top Dukakis aide John Sasso was dispatched to smooth Jackson's feathers.

Still, Jackson faded from the nation's TV screens and front pages this fall. Even now, he works in behalf of Dukakis only selectively, and gets little press coverage. His references to Dukakis are often oblique, but his defense of liberal values is pointed.

Liberalism has many achievements that are now being belittled and denigrated in this campaign by Vice-President Bush, Jackson charges.

``This is a critical hour'' in American politics, he says, because liberal gains could be lost under a Republican White House. ``Despite the enormous civil rights gains of the past three decades, even the rawest forms of racism persist,'' Jackson charges. ``In the first six months of 1988, racial incidents against blacks were recorded in at least 20 states. ... Reports [of racial incidents] from the Community Relations Service of the Justice Department increased by ... more than 400 percent since 1980.''

He continued: ``Something is happening in our country that [saddens] my heart. It is frightening, overt racial aggression against blacks, overt anti-Semitic acts, class rejection of the poor, and exploitation of women workers.''

Jackson says that despite such problems, ``we have the nation's vice-president running for president on the proposition that civil liberties are subversive.'' Jackson charges that Mr. Bush ``stands against civil rights restoration, women's rights, and workers' rights.''

The minister was especially scathing about Bush's frequent use of the phrase ``card-carrying member of the ACLU'' to describe Mr. Dukakis. The words refer to the American Civil Liberties Union, which often defends unpopular causes, both liberal and conservative. Bush's words smack of the Joseph McCarthy-style communist scare campaigns of the early 1950s, Jackson says.

This fall, some Democrats have worried that Jackson could drive away conservative voters from the Dukakis ticket. He has appeared only occasionally in support of the governor. Most of his work is with minority audiences, where he promotes voter registration.

Dukakis's failure to use Jackson more effectively surprises some experts.

``Where is Jesse?'' wonders Thomas Cronin, a political scientist at Colorado College. ``I can't believe they don't have him on the college-campus route,'' says Dr. Cronin. ``He'd be a big hit there for Dukakis.''

Though Jackson hasn't made a big impact this fall, he is espousing populist themes that many Democrats wish Dukakis would use. Samples:

Jackson admits that ``more people are working, yes, but more people are in poverty, which really means profits up, wages down, workers abandoned.''

Jackson scoffs at Bush's efforts to wrap himself in the American flag. ``Salute the flag, yes. Love the country, yes. But more and more of those flags are made in Taiwan and South Korea. We get the joy, and they get the jobs.''

Jackson warns about foreign takeovers of American assets. ``Stand beside the flagpole, yes. But more and more of the flagpoles are in American soil that we are leasing from foreigners. ... We are borrowing from foreigners [and] mortgaging the future of our children.''

Jackson reminds Americans what the popular Republican term ``traditional values'' means to many blacks. He observes that to a plantation owner in the Old South, traditional values meant slavery. Later, traditional values meant Jim Crow laws - ``segregated drinking fountains, back of the bus, segregated schools, parks, bathrooms, restaurants.''

He notes: ``Liberals oppose such discrimination. ... I am going to defend liberalism, and liberation.''

The setback for liberalism began in the 1960s, Jackson says, with Barry Goldwater's campaign for the White House.

``The conservatives began to repackage themselves, and here is where deception comes in. ... Goldwater, `states' rights.' ... George Wallace made busing a ... code word. Spiro Agnew, `the silent majority' - a signal. Richard Nixon, law and order. Signals. Ronald Reagan ... national security. Jerry Falwell, Moral Majority. ... Increased military spending: `Don't let those third-world, nonwhite nations push us around anymore.'''

Crowd-pleasing stuff: with some - but not all - of the crowds Michael Dukakis has to court.