WHEN POLITICS COME TO PUSH & SHOVE : Republicans: George Bush surfboards over issues but Democrats could ride the waves of change--on taxes, abortion and tussles in world trade.

WASHINGTON — Yes, George Bush has achieved record 70%-80% favorable poll ratings while surfboarding on international events and opportunities from Eastern Europe to Panama. Yet not a few Republicans worry that these glories are only a flimsy facade behind which important political dangers fester.

The harsh reality is that few Presidents have made a success out of four years without a significant national agenda, and Bush’s domestic policy--unless bold blueprints for Wednesday’s State of the Union address have been cleverly hidden--is the strategic equivalent of a nudist colony. The political dilemma, bluntly put, is that even if the President can keep his personal ratings reasonably high, long-term ideological trends are going soft.

Three especially dangerous waves for the Administration and the GOP already begin to surge: a rising libertarianism on abortion, a new Social Security-related tax revolt in Middle America and indications that economic nationalism could replace Caribbean gunboat diplomacy as the voter-desired jingoism of the 1990s.

All three developments, moreover, involve major GOP intraparty policy conflicts and strike at underlying cultural, economic and patriotic pillars of the Republic presidential majority that began taking shape more than two decades ago. These changes cannot be staved off with happy talk or clever tactics; they represent something more profound: the increasing obsolescence and exhaustion of yesteryear’s fine-for-1973 and good-for-1981 GOP national-policy solutions.

Abortion, of course, keynotes the cultural turnabout. Along with support for the death penalty and opposition to school busing, right-to-life commitment became a bold banner of late 1970s conservatism. After the U.S. Supreme Court legalized abortion in the 1973 Roe vs. Wade decision, conservative politicians and national GOP platforms could posture for right-to-life backers--and did--while the party’s pro-choice upper-class professionals and career women yawned. Opposition to abortion became one of three or four cultural issues shaping new Republican voting patterns from Catholic South Boston to Baptist North Louisiana.

Until 1989, that is. By reopening abortion to state-level decision-making, the Supreme Court Webster ruling drove a legal wedge into the conservative coalition that united Tennessee fundamentalists with suburban Planned Parenthood voters. As of 1990, GOP gubernatorial contenders are fighting fierce, divisive primaries over abortion in key states from Massachusetts to Texas. Church-going true-believers and upper-bracket sophisticates--at each other’s sides during the 1980s--are now at each other’s throats. The close collaboration of conservative politics and religion, begun in the 1970s, now seems in decline. Jerry Falwell has had to demobilize his Moral Majority and homosexual Rep. Barney Frank (D-Mass.) may even win reelection in suburban Massachusetts, despite letting a male prostitute operate out of his Washington apartment. For the first time since 1964, cultural issues have begun to divide Republicans as much as Democrats.

On the economic front, staunch conservatives and Republicans cemented a 1980s hold on Middle America by suppressing inflation and cutting taxes, two achievements now in some dispute. Inflation shows periodic signs of heating up again, and a New York Democrat has an electrifying proposal to cut Social Security taxes by $55 billion next year: Sen. Daniel Patrick Moynihan has launched a debate that could wind up educating and even embittering voters over who got the tax cuts of the 1980s and who didn’t.

In a nutshell, Middle America got the speeches; upper America got the bucks. For most families, the big tax changes of the 1980s didn’t come in modest federal income-tax cuts--they came in a Social Security tax rate surging from 5.8% in 1980 to 7.65% in 1990, while the income base it applied to doubled from $25,900 to $51,300. A family with one-breadwinner income constant at $50,000 during that period would have seen its Social Security burden swell from $1,500 a year to $3,800. Some “tax-cut decade.”

Meanwhile, however, the top tax bracket for millionaires did come down from 70% in 1981 to 28% in 1988, setting up a stunning comparison. Consider a family with husband-and-wife breadwinners each making $50,000 a year in salary. For income taxes, their combined salaries put them in the 33% rate upper-middle-class “bubble,” and both their incomes are fully taxable for Social Security at 7.65%. That means a combined federal marginal tax rate of 41%, far above the marginal tax rate of 28% paid by billionaires like David Rockefeller or Michael Milken.

Not surprisingly, income and wealth shifted upward. Congressional Budget Office numbers show 7.2% of total national income in the hands of the top 1% of Americans back in 1977; now that same top 1% will have 11.4% of the 1990 total. Should this comparison arouse middle-class voters, the Republicans could lose their 1980s position as the party of tax cuts--and regain their old New Deal-era opprobrium as the party principally loyal to the rich.

Tricky transition No. 3 involves foreign policy. Republicans can no longer count on the “we’re better at dealing with the Soviets” argument, despite its important GOP vote-getting role since the Eisenhower-Nixon years. Public opinion’s new preoccupation, by a large majority, is to consider U.S. interests more gravely threatened by Japanese economic, financial and trade strength--brought to critical mass by policy miscues under Ronald Reagan--than by any military threat from Moscow. And this same psychology lays out the new international playing field where American voters want a game plan to recover the U.S. economic clout and wealth lost to Japan.

With two recent polls showing 60%-70% of Americans glooming that Japan has already overtaken the United States as the world’s leading economic power, 1990s politics are bound to be affected. After the United States was defeated in Vietnam 15 years ago, frustrated American voters slowly but surely embraced military and diplomatic nationalism--even jingoism--over the Panama Canal treaties in 1977, the Iranian seizure of U.S. Embassy personnel as hostages in 1980. The public applauded the invasion of Grenada in 1983, the air-strike against Tripoli in 1986 and the recent invasion of Panama. Each machismo episode underscored Democratic weakness or GOP strength--or both.

Now, however, as voter concern refocuses on the United States’ increasing commercial and financial displacement by Japan--cumulatively a more important defeat than Vietnam--electoral results may reflect that same frustration. And if tough talk on trade and money starts replacing military saber-rattling, domestic politics would change, too. The applause for air strikes and Caribbean invasions once epitomized a popular reaction against long-standing Democartic weaknesses and liberal inability to apply military power. Economic nationalism, by contrast, would draw on voter disenchantment with the Reagan-Bush era slippage caused by White House unwillingness to apply economic power or to interfere with market forces in behalf of protecting U.S. national interests.

All three situations could --none of this is yet certain--signal a metamorphosis of Republican-tilted issues and popular frustrations into pro-Democratic circumstances.

The longer the Republicans control the presidency, after all, the more troubling situations and national difficulties will have developed when the GOP held the nation’s helm. Even Democrats will begin to see more and more opportunities for criticism and attack.

For the moment, as his high ratings bear witness, Bush is successfully managing the transformation--in part by ignoring it, and in part by playing a string of yesterday’s trumps. He has used gunboat diplomacy, anti-crime rhetoric and drug-control bombast. But they will not be enough. The real test--first, in Bush’s Wednesday State of the Union message, and then in his follow-up actions--is whether the President can seriously address three incipient mood-shifts and role-reversals that threaten to rescript U.S. politics and ideology in the 1990s.