Reagan's next hurdles. Providing details, getting cooperation

President Reagan has sought to demonstrate that he is fit, remains spunky, and has lost none of his flair for delivering a speech. But in the wake of his sixth State of the Union address, the White House remains challenged on two fronts:

First, it is far from certain that the President's brief reference to the Iran-contra affair as his one and only ``major regret'' will suffice to dispel public doubts about his policy toward Iran or about his own role in the affair. Democratic lawmakers and many political experts feel that Mr. Reagan could have bolstered himself politically by going further than he did - that is, not only accepting ``full responsibility'' for ``serious mistakes'' made but specifying what the mistakes were.

``It's not clear whether the mistakes are just technical mistakes in the execution of [his policy] or whether there is something in the way of providing arms as ransom for hostages that he thinks is wrong,'' said House majority leader Thomas S. Foley yesterday.

The President does not need to apologize or humble himself, Mr. Foley stressed, but he needs to say whether he still regards the sale of arms to Iran as a useful tool to improve relations with alleged Iranian moderates or to get the American hostages out. If he does, the majority leader said, there ought to be a public debate of the issue.

Second, the administration is under a challenge to show that it has a substantial program that will get at the nation's problems. In keeping with the usual style and tone of State of the Union speeches, the President confined himself to generalities and rhetoric. He aired familiar themes and legislative proposals, but gave no specifics.

Judging from polls, there is a growing sense among the American people that the nation has been stockpiling problems, from the budget and trade deficits to jobs and education. The televised Democratic response to Reagan's address by House Speaker Jim Wright and Senate majority leader Robert Byrd indicates that the Democrats are no longer afraid to take on the President on these issues.

The question now is whether Reagan will come up with detailed proposals that have public support and work cooperatively with a Democratic Congress to negotiate compromises. Here is the present outlook for key legislative items mentioned by the President:

The budget deficit. There is a wide gap between the Congress and the White House on meeting the Gramm-Rudman deficit-reduction target for fiscal '88; each side works from different assumptions about economic growth in drawing up the budget. But the gap is not as bad as in previous years, and the Reagan budget, which includes a 3 percent real increase for defense and $22 billion of new revenue (despite the pledge of no new taxes), provides a starting point for compromise.

Economists point out that, because of congressional action, the structural deficit is already on a downward path even without a tax increase and, though troublesome, is not as worrisome as it was a few years ago.

Balanced-budget amendment and line-item veto. These are perennial presidential proposals but have no prospect of passage.

Trade and competitiveness. The administration has yet to signal what kind of ``fair trade'' legislation it will support. Lawmakers are expected to pass a bill incorporating limited protectionist measures, which the President has consistently opposed.

Today's new catchword is ``competitiveness,'' and the President's focus on educational standards, scientific research, and ``excellence'' is in tune with the current mood. But the Democrats charge that Reagan's proposed $5 billion cut in federal spending for education belies the seriousness of his rhetoric.

Welfare reform. There is a growing view even among Democrats that something must be done about welfare without increasing federal resources for it. But the White House has yet to spell out its program.

Catastrophic health care. Both Congress and the President are prepared to take action. But there is dissension in the administration about what kind of insurance program to propose.

The Strategic Defense Initiative. The President says he is determined to pursue his program for a space-based antimissile defense shield. But Democrats and many Republicans in Congress are prepared to hold down the SDI research budget. If the President decides to go ahead with an early deployment of an SDI system - as Defense Secretary Caspar Weinberger and other hard-line aides are conspicuously advocating - Congress is certain to block the move.

The Nicaraguan contra rebels. The President only indirectly raised the issue of more aid for the contras, vowing to fight any effort ``to shut off their lifeblood.'' But he and Congress are expected to be on a collision course on this issue. After the Iran-contra fiasco, which included the unlawful diversion of funds to the contras, the Democrats are more determined than ever to halt all such assistance.