The White House and Republican congressional leaders have missed their best chance to defuse Mario Cuomo's tax-increase time bomb that will greet the next president.

Although Republicans were given half the seats, no member of the new National Economic Commission's 12 members is a supply-sider, a strong foe of tax increases or an architect of Reaganomics. Efforts to get even one taxophobe out of two appointments each by President Reagan, Senate Republican leader Robert Dole and House Republican leader Robert Michel all failed.

So the GOP selections announced Feb. 19 fit the new commission's consensus that American taxpayers should pay more to support their bloated government. The commissioners need decide merely what kind of tax increase.

With presidential primary voters in both parties reiterating that enough is enough when it comes to taxes, the NEC is an elitist short-circuit of popular opinion. When the commission reports March 1, 1989, a Democratic president could humbly accept this verdict from wiser heads. A new Republican president, having just pledged no higher taxes, may find it embarrassing.

New York's Gov. Cuomo devised the scheme after the Oct. 19 market crash. With Dole eagerly supportive and the administration passive, it was tucked into the session-end money bill. The NEC imitates the 1982 Greenspan Commission, which pushed through unprecedented Social Security tax increases that Congress never would have passed on its own.

The previously named six Democratic commissioners make up a murderer's row of tax increasers: Sen. Daniel Patrick Moynihan, Rep. William Gray, former Democratic national chairman Robert Strauss, AFL-CIO President Lane Kirkland, Chrysler's Lee Iacocca, Wall Street financier Felix Rohatyn. All want a major tax increase.

Before the Republican six were named, ordinary Americans reinforced disdain for paying higher tribute to Congress. Tax booster Bruce Babbitt was overwhelmingly rejected by Iowa and New Hampshire Democrats. Rep. Richard Gephardt won Democratic votes by defending his support of Reagan tax cuts. Dole's advisers concede he met disaster in New Hampshire because of the tax-increase stigma. Vice President George Bush's surrogates stressed Dole's collaboration with Moynihan in enacting the NEC and plan repeating that theme in the Super Tuesday primaries.

This climate seemingly favored Republican appointment of supply-siders who would prevent replication of the monolithic Greenspan Commission: Paul Craig Roberts, Jude Wanniski, Arthur Laffer. Pleas were made to Ken Duberstein, White House deputy chief of staff, to counter protax labor leader Kirkland with an antitax U.S. Chamber of Commerce official.

Instead, the president appointed two former Cabinet members -- ex-defense secretary Caspar Weinberger and ex-transportation secretary Drew Lewis -- to defend his administration. Although Weinberger never was tempted to protect his Pentagon budget with higher taxes, he is no supply-sider. Lewis is remembered in the early Reagan administration for plugging gasoline taxes, which may indeed be the choice of the NEC.

It was thought in conservative House circles that out of a host of recommended antitaxers, Michel might name U.S. Chamber of Commerce chief economist Richard Rahn. Instead, he selected Rep. Bill Frenzel and ex-representative Donald Rumsfeld, neither of whom is taxophobic.

That left appointment of an antitaxer to Dole, bitter after rejection in New Hampshire as a taxer. He was advised to attempt a coup by naming former presidential candidate Pierre du Pont, who in the last New Hampshire debate called Dole's bluff on an antitax pledge. Too late. Dole had decided on Sen. Pete Domenici and American Farm Bureau Federation President Dean Kleckner.

Dole appeared to be balancing protax Domenici with the Iowa farm leader's longtime opposition to higher taxes. In fact, the senator named Kleckner as a midwestern farm voice without knowing his tax position. After offering him the appointment following the New Hampshire primary, Dole asked Kleckner whether he favored tax hikes. When told no, the senator replied in words to this effect: Good, that's what I need now.

But Kleckner alone cannot stand off the NEC's taxing heavyweights. Nor can the president-elect's two appointments named after Nov. 8. Moreover, Dole's position is ambiguous as a commission godfather while other GOP hopefuls -- Bush, du Pont and Rep. Jack Kemp -- were negative about the NEC. When Cuomo visited the vice president to push the idea last year, Bush refused to say yes and told campaign manager Lee Atwater it looked like a gimmick for higher taxes.

Why then did the vice president not secure an antitaxer's appointment to the NEC? If nominated and elected, he will get a final chance to muffle the time bomb's impact with two additional appointments. But when the commission's inevitable demand for higher taxes reaches the new president's desk a year from now, nobody can be certain whether George Bush would just say no.