THE DOMESTIC BUSINESS of the Reagan administration is mainly over. That was the message of the president's State of the Union address Monday night. There are lots of things the president doesn't want this Congress to do -- pass a certain kind of trade bill, increase welfare benefits, raise the minimum wage. But the things he badly does want it to do -- bless the INF treaty, extend aid to the contras -- have to do with foreign affairs. The tax, defense and even domestic spending fights of earlier years have faded. On these issues he and Congress declared a hollow truce last November, and now seem content to coast.

That means, of course, that the deficit will be bequeathed to the president's successor. The next president and Congress will start off $160 billion in the hole, and good luck to them if there is a recession or they have in mind to do anything but pay this administration's bills. The president went through his usual ritual on the deficit. Having led in its creation, he then also led in its denunciation -- and ascribed it less to policy than to process. Having doubled the national debt in seven years he called again for a balanced-budget amendment to the Constitution. From whom do we need to be protected? He also asked for the line-item veto, which Congress won't give him, nor should it. It would mean that no spending item could be approved over a president's objection without a two-thirds vote in both houses; that's too great a shift of power.

The president then said he would pluck from the continuing resolution that he signed last month all the items he would have vetoed if he had had the line-item power and send them back to Congress as a proposed rescission -- a request that the two houses reconsider and cancel the appropriations. That's a grand idea, and we hope it passes, for two reasons. The porkier items that the president indicated he proposes to include don't belong in the budget, and the exercise may demonstrate not merely the strengths -- as the president intends -- but the limits of the line-item idea. The deficit isn't $160 billion and holding because of pork. It's there because taxes have been cut below the level required to sustain the combination of national defense and federal services the country wants and probably ought to have. That may not be quite the state of the union as this administration ends, but it's surely the state of the government.