Washington — A potential confrontation looms between President Reagan and Congress over what a senior White House official calls a "sleeper," in the budget process. The "sleeper," says Deputy Budget Director Edwin L. Harper, could "erode away" some of the $35.2 billion in savings that Mr. Reagan and the American people thought had been achieved in the 1982 budget.
Mr. Harper was referring to the fact that congressional committees are appropriating more money for specific programs that will fit under the roof nailed down by the 1982 budget.
The President has voiced his concern and White House officials speak of possible presidential vetoes of spending bills if Congress ends up breaking the budget.
also concerned are the chairmen of the House and Senate Budget Committees -- Rep. James R. Jones (D) of Oklahoma and Sen. Pete V. Domenici (R) of New Mexico -- both of whom, said a congressional source, "take the budget seriously."
Politically, in other words, some powerful figures -- Reagan and Messrs. Domenici, Jones, and others committed to making the budget process work -- deplore spendiing overruns. Yet they are happening.
Already the House, according to a senior White House official, is $2.7 billion over the agreed-upon 1982 spending figures, with a number of appropriations measures still to be considered.
It works like this:
Congress, through the Omnibus Reconciliation Act of 1981 adopted July 31, gave Mr. Reagan what he wanted -- $35.2 billion worth of spending cuts in the 1982 budget.
Because many government programs involve multiyear commitments, the savings would increase in future years, yielding $130.6 billion in cuts over the 1982-84 period.
A part of these savings are in "entitlement" programs -- transfers of money to Americans who qualify for help because of age (social security, for example), disability, income level, or other reasons.
Congress changed the eligibility rules on some of these programs, to yield $ 13.4 billion in fiscal 1982 savings and $43.8 billion over three years. These savings are automatic and require no further congressional action.
That leaves nonentitlement programs, for which $21.8 billion in spending was cut. The Reconciliation Act did this by reducing "authority" for actual outlays.
Then comes the next step -- appropriations. Each congressional committee appropriates money for programs within its purview. These should add up to no more than the authorized amounts.
In fact, they are adding up to a lot more. Altogether, the House and Senate must act on 13 separate appropriations bills for fiscal 1982.
When Congress left Washington for the August vacation, seven of the measures had been approved by House committees, of which five have passed the full House. Two are out of Senate committees, with one passed by the full Senate.
The process, in short, is about half finished or, as a senior congressional analyst put it, "way behind schedule."
These seven measures, according to White House officials, approriate $2.7 billion more than the agreed- upon levels for fiscal 1982, plus another $2.74 billion in overruns during the 1983-86 period.
"This," said a White House official, "is the best estimate of the Office of Management and Budget of what actual outlays would be over the President's budget."
Some huge appropriation bills -- including the Defense Department and the Health and Humans Services Department budgets -- remain to be passed. So the spending overruns could grow.
What will happen? "Everything," said a congressional budget expert, "is very messy right now."
Congress is due, by Sept. 15, to adopt is so-called second resolution on the 1982 budget, which is supposed to be binding on spending totals.
Congress could simply swallow the increased outlays voted by committees and boost the budget, thereby shrinking the projected savings and swelling the deficit.
This would provoke a sharp challenge from President Reagan, on the grounds that Congress was going back on a solemn commitment.
Even if Congress slashes its spending plans and stays within the agreed-upon 1982 budget, said a congressional source, "Spending is likely to be $12 billion to $15 billion higher than the White House wants, through no fault of anyone."
He cited as an example high interest rates, which are adding billions of dollars to the government's interest payments on the national debt.
If unavoidable do boost fiscal 1982 spending, Reagan appears to have two choices:
* Go back to Congress and propose fresh spending cuts, designed to whittle the swelling budget back to the size set by the Reconcilliation Act.
* Agree with Congress that spending has to be higher because of factors beyond anyone's control, such as interest rates .