An immediate, across-the-board cut of 2 percent in federal spending to fight inflation was recommended yesterday to President Carter by leaders of the National Association of Realtors.

The group said it told the president and his advisers that the 762,000 NAR members are concerned about high borrowing rates and a 35 percent decline in housing sales across the nation. The NAR promotes a 2 percent cutback in federal spending during the next 18 months to reduce interest rates and encourage savings to enable more persons to buy homes.

Ralph W. Pritchard, NAR president, said after the White House meeting that Carter had listened attentively to the message.

The realtor's pleas for a "2 percent solution," which appeared yesterday in paid advertisements in major newspapers, was presented to Carter and his advisers on the premise that it would balance the budget at $595 billion, reduce inflation by 3 percentage points, lower short-term and long-term borrowing rates and permit one million households to move to better living quarters each year.

The NAR position is that a 2 percent cutback in federal spending would be the "easiest solution" to the problems facing the economy and would trigger lower borrowing rates, which would benefit home builders and home buyers.

Yesterday's White House visit by Pritchard and Carlson culminated a series of meetings held here Monday and Tuesday by the legislative arm of NAR.

In other meetings, NAR members heard Jay Janis, chairman of the Federal Home Loan Bank Board, predict a further drop in 1980 housing starts and sales of existing homes. He also said that he regards locally enforced moratoriums on condominium conversions of rental apartments to be an illegal means of depriving individuals of their rights to own property.

Sen. Edmund Muskie (D-Maine) endorsed a balanced budget for fiscal 1981. He added: "A tax cut next year will depend on the political heat you apply" to the Congress.

Rep. Barber Conable (R-N.Y.) told the group that the budget must be balanced "because of fiscal discipline or the American people won't accept it."