THE spring battle lines are being drawn.
When Congress returns from its break, the stage will be set for this century's most significant political contest between a president and a Speaker of the House. At stake is the middle class vote, a constituency vital to both in the 1996 elections.
Speaker Newt Gingrich has controlled the agenda since last November's midterm elections swept him into power. President Clinton took a back seat during the first 100 days.
But the House GOP Contract With America, with its welfare and regulatory reforms, line-item veto, and tax cuts, was simply a ''preliminary skirmish to the big battles yet to come,'' as Mr. Gingrich put it in a national speech Friday night.
Already, Clinton is starting to speak out, threatening to veto some of the key bills passed by the House. Skirmishing over the budget and core Democratic issues, such as affirmative action, is expected to intensify as the two leaders clash over their competing visions of government.
At this point, Gingrich still has the upper hand, says John Cogan, a senior fellow at the Hoover Institution in Stanford, Calif.
With the GOP running the agenda from the outset, he says, Clinton lost a vital period of control. Normally, the president makes a series of proposals and Congress responds.
''For the first three months of the year, the president usually dominates the agenda,'' he says. ''All the proposals come from the White House. But by March or April ... the congressional debate over the budget drives the national attention. It is hard to see where the president will get the advantage.''
But Ron Peters, a political scientist at the University of Oklahoma, in Norman, Okla., argues that the president has built-in advantages that will, in the long run, become apparent.
''No doubt Bill Clinton is on the defensive,'' he says. ''But that will slowly turn. The constitutional system requires the president to be the center of gravity in terms of initiative.''
In the coming months, Republican budget efforts will reflect an attempt to radically reduce and reshape Washington. Gingrich and the GOP have proposed cutting four federal agencies, revising the income tax structure, and dismantling the welfare state.
But to balance the budget by 2002, as promised, the Republicans will have to cut deeply into such middle-class entitlement programs as medicare and medicaid. And that puts Gingrich and Company on shaky ground.
Ron Milacsky, a communications science professor at the University of Connecticut, in Storrs, Conn., argues that while the public supports the idea of a balanced budget, that support dissipates when cherished programs are trimmed.
The Democrats have already successfully exploited Republican proposals to decrease projected spending on school lunches.
''That's how the middle class will be energized,'' Professor Milacsky says. ''As the Republicans gore each ox,'' the Democrats have an opportunity ''to mobilize such middle class constituencies as labor, women, and blacks.''
Professor Peters agrees: ''Bill Clinton will be a counterpuncher in the next two years. And counterpunchers win fights. Tough times for the Republicans are coming. It will be hard to hold the line when they have to make the cuts.''
So far, the Clinton strategy has been to sit back on the ropes. While the Democrats' defeat in last November's elections has forced the president to abandon his more ambitious goals such as universal health-care reform, he isn't likely to be as docile about what he calls Republican plans that are aimed at the most vulnerable segments of society -- children and the poor.
He advocates relatively modest tax breaks for the middle class and a higher minimum wage.
The Senate may end up playing the role of referee between Clinton and Gingrich. And its bias isn't clear yet.
The upper legislative body may act as a kind of buffer for House Republicans, moderating some of their tougher budget provisions before sending them to the president.
But if it lumps major bills together, Clinton may be forced to accept items he would have rejected separately, to avoid vetoing a major budget initiative.
''If the Senate and Newt Gingrich get into balancing the budget without cooperation from the White House,'' says David Mayhew, a political scientist at Yale University, in New Haven, Conn., ''it will be politically dangerous.''
But the hallmark of the Senate is bipartisanship, which may be the key to Republican success. Though skeptical early on, Senate Republicans appear to be moving closer to several of the House provisions, including tax cuts and welfare reform.
''If I were the Senate Republicans, I'd try to get the Democrats into bipartisan dealmaking,'' Professor Mayhew says.
''If a balanced budget initiative has bipartisan support in the Senate, the White House would have to make up its mind: Go along or throw darts. Politically, its a close call.''