You may yet hear this voice from '68 in 1984 election

Consider this problem: You're a Democrat, and you think the party's field of presidential candidates is as bland as overcooked pasta. Walter Mondale doesn't make your voting hand twitch; John Glenn seems an Eisenhower from outer space; and you can't follow all of Jesse Jackson's rhymes. You want a candidate who's inspiring, who has a coherent vision of what America should be. You want . . . Eugene McCarthy.

Eugene McCarthy?

''I haven't put running out of my mind altogether,'' says Mr. McCarthy, a former senator from Minnesota, veteran of two presidential campaigns, once leader of a devoted army of youth. ''I've got some meetings scheduled around the country. Perhaps I'll enter the primaries in five or six states.''

McCarthy is semiretired now, living on a farm in rural Virginia (''10 acres, no livestock''). But his memorable wit is as honed as ever. In recent months, he has characterized Mr. Mondale as a man with ''the soul of a vice-president,'' said Senator Glenn is running as Dwight Eisenhower, and accused Gary Hart of trying to be ''all the Kennedys.''

''So far, the campaign is almost like one of those bicycle races where they go as slow as they can for the first 20 laps,'' he says in his slow, quiet voice. ''I don't really see them presenting issues that deal with the kind of functional disorders we have today in US society.''

Unemployment, for instance. McCarthy says he's tired of hearing the same old crooning about more job training and public works. He favors ''redistributing'' jobs by cutting the workweek to 35 hours.

''We're always demanding redistribution of land in South America, and the principle involved here is the same,'' he claims. ''A job is the only kind of property many Americans have.''

Then there's energy (an issue McCarthy feels the candidates have forgotten) and the arms race, of course, and all-around waste in American society, and the power of multinational corporations (''maybe we should have diplomatic relations with large companies''), and the threats to liberty posed by the Internal Revenue Service and its handmaiden, income-tax law.

McCarthy is flying now, up in the stratosphere of liberal ideas, where he loves to be. He leans forward in his office chair. Occasionally, a smile flashes across his face, followed by a rumble of wit as thunder follows lightning.

''Gene really has one of the keenest intellects in politics,'' a longtime associate sighs. ''If only he could have pulled it all together and been elected president.''

Probably no US politician in modern times has matched Eugene J. McCarthy's ability simultaneously to enthrall and frustrate followers.

In 1968, his antiwar candidacy attracted thousands of young volunteers and swelled into a ''Children's Crusade'' that helped topple a sitting president. Yet some aides feel that McCarthy, at times, sabotaged his own effort. He would skip campaigning for long conversations with friends such as poet Robert Lowell; a crucial summer weekend was spent at St. John's University, where McCarthy rested, watched baseball's All-Star Game, and played softball with nuns.

''He didn't want to be a leader,'' says a magazine writer who covered the campaign. ''He set himself up for it, but he didn't want to lead.''

In 1970, McCarthy quit the Senate. In '76, he ran again for president, but spent much of his time in court, challenging restrictions on independent candidates. In '82, though many advised against it, he tried to regain his Minnesota Senate seat - and was soundly beaten.

Although he spent 21 years as a nuts-and-bolts member of Congress, McCarthy in the end has seemed less interested in obtaining power than in promoting what he views as a rule of reason. ''His need to find transcendent meaning sometimes frightened me,'' writes McCarthy's estranged wife, Abigail, in her book ''Private Faces/Public Places.'' ''I thought him too idealistic for politics.''

McCarthy lives in Woodville, Va., a hunt-country hamlet that is little more than a postbox. He works before the giant, 18th-century fireplace in his farmhouse, writing essays for the Rappahannock (Va.) News, Country Magazine, The New Republic, and others.

These pieces, for the most part, are less than weighty. Among other things, McCarthy has advocated bringing back the cavalry as an arms control bargaining chip, urged the use of muffin-mix sales as a leading economic indicator, and condemned (mildly) a government plan to eliminate Washington's pigeons. ''Pigeon experts know that pigeons cannot be exterminated,'' he writes, solemnly. ''At most, they can be moved about.''

And even out of public life he has continued to do things that confound his friends. For one thing, there is this talk of another presidential run.

''Oh, no!'' says one associate, in response to a reporter's query. ''He told you that? I've already had several people call me up and say, 'Please, don't let him do it.' ''

Then there is the fact that McCarthy, in earlier years the very model of a modern major liberal, endorsed Ronald Reagan in 1980.

''Well, I did [endorse him], principally on economics,'' McCarthy says. ''We just couldn't tolerate another four years of Carter's fiscal irresponsibility.''

While he doesn't approve of the manner in which Mr. Reagan wrung inflation out of the economy, he says, at least it was done. And while Reagan's foreign policies are horrendous, he adds that they're not much different than those of the Carter administration.

McCarthy seems particularly bitter about Jimmy Carter, and the effect of the Carter years on the Democratic Party. The Democrats, in his eyes, staggered away from the 1980 elections as an organization in search of a program. Since then, yet another set of rule changes has made it less likely that the party will come up with fresh faces and new ideas, he charges.

''The new rules have, in effect, given control of the Democrats to the same blocs that controlled the convention in '68, the party regulars and the labor movement,'' McCarthy says.

McCarthy also rails against what he calls the increasing ''stranglehold'' of the two major parties on American politics. State laws, press apathy, and the ' 74 Federal Election Act (which authorizes federal matching funds for presidential candidates) are combining to shunt independent candidates aside, he complains. In his eyes, this just ''gives the government that much more control over the political process.''

Is this, then, why McCarthy ran for the Senate last election, and continues to muse about another presidential bid? To combat what he views as the ''bureaucratization'' of democracy? Perhaps - but Eugene McCarthy, as his associates are quick to point out, is not easy to understand. The motivations of a man who, while campaigning for president, pauses to write verse titled ''Three Bad Signs'' can only be guessed at.

In ''Year of the People,'' his story of the '68 campaign, McCarthy approvingly quotes William Butler Yeats:

''Nor law, nor duty bade me fight,/Nor public men, nor cheering crowds,/A lonely impulse of delight/Drove to this tumult in the clouds. . . .''