The hectic scramble for votes as West German political parties steam toward March elections has created rifts within the ruling center-right coalition over key issues of nuclear missile deployments and economic policies.

Chancellor Helmut Kohl's campaign has sought so far to emphasize support for the U.S. missiles strategy and for doses of austerity to revive the economy. But lukewarm public response has prompted the coalition junior partner, the Free Democrats, to lurch in different directions for new votes to stave off extinction.

As Soviet Foreign Minister Andrei Gromyko departed today after a three-day visit, it became evident that a tactical breach still divided the Christian Democrats and the Free Democrats over the best way to nurture an agreement between Moscow and Wasington that would restrict or eliminate medium-range nuclear missiles from Europe.

Kohl stressed to Gromyko that the Bonn government held a "firm, clear position" in favor of President Reagan's "zero solution" that would cancel deployment of 572 Pershing II and cruise missiles if the Soviet Union dismantles 600 or more nuclear-tipped rockets targeted on Western Europe. The government also announced that it was sending its disarmament expert, Friedrich Ruth, to Washington Wednesday to discuss the current state of the arms talks.

But the Free Democrats' leader, Foreign Minister Hans-Dietrich Genscher, is now calling for "an interim solution" that would keep the missile count low on both sides if the ultimate goal of total elimination could not be achieved this year.

In a radio interview today, Genscher argued that a shift away from the zero option should be undertaken if the Soviet Union showed signs of reciprocal compromise. Genscher's views were backed by Jurgen Moellemann, a Free Democrat foreign affairs specialist, who said an "all or nothing" approach on the missiles could not be accepted and the West must prepare for "an interim solution."

As the parties here scramble for votes in the upcoming March election, the missile debate has become motivated more than ever by political considerations.

When Kohl took power in October, he sought to quell fears about a neutralist trend here by emphasizing Bonn's commitmente his rhetoric to l1 ** 9 ='D! ho are uncomfortable about missile deployment regardless of the fate of arms talks.

At the same time, the opposition Social Democrats have rebounded from a nadir of 30 percent to 42 percent this week, second only to the Christian Democrats' 48 percent ranking. The antinuclear, environment group known as the Greens polled 6.2 percent support.

The Social Democrats now stress the need to negotiate the most plausible deal with the Soviets to avoid new nuclear deployment. They have displayed strong momentum in the campaign, particularly in the wake of highly publicized trips to Washington, Moscow and Paris in recent weeks by their candidate for chancellor, Hans Jochen Vogel, who has embellished their image as the party best endowed to revive detente.

Vogel's journeys also highlighted the impression that the Social Democrats are determined to become actively involved in seeking a compromise between the superpowers, a role that contrasts sharply in the public eye with the Christian Democrats' less flexible posture of unflinching fealty to Washington's line.

The Social Democrats' deputy leader of parliament, Horst Ehmke, today outlined a compromise solution for the Geneva talks that he said the United States should propose to break the impasse.

Ehmke said the United States should revoke deployment of the 108 Pershings and station only half of the 464 cruise missiles in return for the Soviets' agreement to dismantle half of their 333 SS20 missiles, the newest of their arsenal.

While admitting that this arrangement would leave Moscow with a superior intermediate missile force in Europe, Ehmke said his proposal "would underline the defensive nature of NATO" and possibly encourage the Soviets to prove more cooperative in seeking an overall balance in strategic arms reduction talks.

The Social Democrats' proposal may sow even more discord between the ruling coalition parties if the arms talks languish and the Free Democrats grow more restive about improving prospects for a compromise in order to capture enough votes to survive the March elections.

There is also growing disunity between the two parties over economic policies. On Monday, Kohl's Christian Democrats stunned the Free Democrats by imposing a surtax on incomes above $21,000, a move prompted largely by concern that the party was losing ground to opposition charges of being a "socially unjust" rich man's party.

The Free Democrats believe in trickle-down economics and argued in vain that the tax must be repaid to restore investment incentives and business confidence.

Free Democrats said they were "astonished" by the decision because the idea of a surtax of upper incomes was the primary reason their party jilted a coalition with the Social Democrats to form a government with the Christian Democrats.