Just how much Democrats learned from their Election Day debacle will be flashed Dec. 10 by the House Democratic causcus when it decides whether to plan an LBJ disciple, targeted for extinction by liberal political activists, in a post of tactical leadership.

Rep. James Jones of Oklahoma is slightly favored over his principal opponent, Rep. David Obey of Wisconsin, to be elected chairman of the House Budget Committee -- the point man confronting Ronald Reagan's overall program. Superficially, they are similar: tough, smart, young (Jones is 41; Obey is 42) and new legislative masters of the House.

But seldom have Democrats been offered a clearer choice of how they should react to defeat. Obey is a skilled practitioner of liberal constituency-group politics who wants to reform big government sufficiently to save it. Jones wants to throw out liberal spending paraphernalia that has collected in the Democratic attic for generations.

Tried-and-true liberals have viewed Jones as Judas Iscariot ever since he guided through the House the 1978 tax reduction bill backed by Republicans and opposed by President Carter. He is on the secret hit list of the National Committee for an Effection Congress, the famous liberal political action group, for 1982 Democratic primary defeat by a liberal in his conservative Tulsa district.

By supporting corporate tax incentives for industrial expansion, Jones has earned cloakroom indictment by liberal colleagues as a mouthpiece for the Business Roundtable. "The mouthpiece for the Business Roundtable. "The problem with Jimmy," one such congressman told us, "is that he'd give the store away to the Republicans."

Actually, Jones he voted recently, 32 percent liberal, according to the Americans for Democratic Action and 45 percent conservative, according to the American Conservative Union. That compares with figures of 89 percent liberal and 11 percent conservative for Obey and 74 percent liberal and 3 percent conservative for Rep. Paul Simon of Illinois, who is running a poor third for budget chairman.

Obey is the current chairman of the Democratic Study Group, the House liberal caucus. On the budget committee, he protected health and education spending from many assaults and opposed all increases in defense spending. On the House floor, he manned the barricades against anti-abortion riders. Last spring, Obey talked the Carter administration into relaxing domestic spending restrictions, much to the mortification of Jones.

Differences between Obey and Jones over tactics may be even more significant. Jones, a junior aide to President Lyndon Johnson in the mid-1960s, would imitate tactics employed by Senate Majority Leader Lyndon Johnson in the 1950s: oppose the Republican administration only rarely; but when a constructive alternative is in hand, attack in force.

Thus, in reacting to Reagan's tax program, Jones supports tax cuts in principle but would apply a Democratic twist by making upper-in-come-bracket reductions conditional on investment. Jones wants a Democratic label on relief for middle-income voters (earning up to $40,000 a year) who abandoned Jimmy Carter a month ago because they felt the Democrats had abandoned them.

Obey as budget chairman would resist far more than Jones the Reagan run at cherished social welfare programs. That stance is clearly more congenial to Speaker Thomas P. O'Neill, as well as to many Democratic congressmen who will vote for Jones in caucus anyway.

The reason is that they agree with Jones that their party has elimanated blue-collar voters as the proponent of federal social engineering, the opponent of a strong defense and the defender of permissive personal conduct. That image would not be softened by House Democrats' persisting in voting patterns followed by Dave Obey until now.

Jones believes Democrats must change both image and policy to reassert themselves as the majority party. He has told friends that the views of represemt the 1970s, not the 1980s, and as such offer no effective alternative to Reaganite Republicanism.

Unlike the preceding two House Budget Committee chairmen, Jones would also sit on the tax-writing Ways and Means Committee, where he has grown influential. That gives him unique leverage on the broad scope of government policy, perhaps as a prelude to future leadership. Nobody in the House doubts that Jimmy Jones wants to be speaker someday, particularly not after he turned down a promising race for the Senate this year.

The vote caucus, therefore, will determine whether he manages the first big step on the slippery ladder to the spealership. But beyond one politician's fate, it will provide the first concrete evidence of whether the Democratic Party truly feels compelled to change its ways after unmistakable rejection by the voters.