The official confirmation of Professor of Economics Martin S. Feldstein '61 as chairman of the Council of Economic Advisers (CEA) has become enmeshed in election-year politics, and the once certain event has now been delayed at least until December.

Democratic senators, who gave the conservative economist a hard time at his confirmation hearings last week, have succeeded in stalling the approval process, preventing the full Senate from okaying the appointment before it adjourned last night to, the final week of campaigning The necessary vote cannot take place until the body reconvenes in late November.

Senate confirmation, though required by the Constitution, is usually a mere formality Members of both parties generally acknowledge that while they may disagree with the nominee's ideas, the President has a right to choose his own advisers.

But with a crucial mid-term election only six weeks away, the Democrats have used the confirmation of Feldstein as a lightning rod for their criticisms of Reagan's economic policies--the major theme of the campaign

At the two-hour Senate Banking Committee September 22, Feldstein was grilled for proposals he had made in the past to trim social security spending and divert resources away from housing programs.

Senators also criticized him for the size of his personal wealth, saying he was one more in a line of millionaire appointees. At one point, when Feldstein stated that he was worth $750,000, Sen. Donald W. Reigle Jr. (D-Mich.) angrily walked to the witness table and presented documentation showing that, including personal savings, the 42-year-old professor is worth $1 million.

When the committee took up the matter again this Thursday, the vote split directly along party lines. Seven Republicans voted in favor of confirmation; five Democrats took the unusual step of voting against Four senators were absent.

"It's the Democrats' way of expressing anger over the President's economic priorities." an aide to Sen. Alan Cranston (D-Calit) who registered a "no" vote-said earlier this week.

But the minority carried their protests beyond the simple vote. The matter should have proceeded directly to the Senate floor yesterday, where it most likely would have breezed through. The minority, however, took advantage of a rarely used procedure, asking for a written report on the nomination.

That request--which aides said would take a few days to fill-effectively prevented the confirmation from reaching the Senate floor yesterday. When the Senators adjourned early this morning, they had not considered it.

Reagan may make Feldstein temporary official chairman by using an obscure constitutional provision allowing appointments during a Senate recess, a CEA staffer said. But a White House spokesman refused to discuss that possibility yesterday, saying only "we hope that Professor Feldstein will be confirmed this afternoon."

Should Reagan exercise such authority, the Senate would still have to approve the appointment in its lame duck session.

Whenever the vote does come up, nobody predicts Feldstein will lose.

The Senate has apparently not flustered Feldstein, who was unavailable for comment yesterday. "Marty understands politics," one assistant said.

The whole complication has little more than symbolic importance anyway, since Feldstein and his crew--confident of eventual approval--have already taken over the office.