Democrats now may have found their big political issue in what they charge is President Reagan's agreement, in principle, to cut social security.
That agreement came, they say, with Reagan's endorsement last week of the Senate budget compromise, which includes $40 billion in unspecified savings from social security over three years. The President has said that the cuts will not affect recipients' cost-of-living increases.
Actually, Mr. Reagan opposed including social security cuts in the budget put together by Senate GOP leaders. But he was told that he had to agree to such cuts or the budget resolution would move ahead anyway, without him.
So, in the end, Reagan agreed to what some of his people in the White House concede is a very ''hot potato.'' Now the President is trying to avoid becoming the target of criticism by saying that any position he will take on social security cuts will await the recommendation of a commission studying social security's solvency.
White House officials contend that when the committee issues its report -- expected sometime after the fall elections -- action to ensure social security's solvency will be bipartisan, with the President and Congress working together on a solution.
The big unanswered question is, says one White House aide, ''How is all this going to play with the voters?''
The Democrats are jumping in fast and hard in an effort to publicly portray Reagan as a President playing fast and loose with the incomes of the senior citizens.
Senate minority leader Robert C. Byrd (D) of West Virginia charged that by backing the Senate plan, the President was showing a willingness to mortgage the economic future of the elderly ''to finance the economic folly'' of Reagan's three-year tax cut.
House Speaker Thomas P. (Tip) O'Neill Jr. (D) of Massachusetts said the President was seeking to ''correct the inequities and excesses'' of his tax cuts by putting a burden on the elderly.
To dramatize the charge that the President was taking a position against older citizens and that Democrats were not, Senator Byrd and Sen. Daniel Patrick Moynihan (D) of New York introduced an amendment to a defense bill that would permit Democratic senators to express their rejection of Reagan's social security position.
In accepting the Senate budget plan containing the social security cuts, the President was well aware that he might be taking on a political bombshell. Not long after becoming President, he stirred up an angry response from the elderly when it was reported that he was looking at the possibility of raising the minimum age for social security eligibility.
Reagan immediately pulled back, letting it be known he had no such plan and that instead, he would follow a bipartisan approach to achieve solvency for social security.
Democrats say that by approving the social security cuts embraced in the GOP-Senate plan, the President has again indicated he is taking the lead in seeking to shrink social security benefits, despite his assurances. This is the kind of recognition that no leader in this city is seeking.