President Reagan's senior advisers and political strategists gathered at Camp David without the president yesterday for a high-level session focused on 1982 presidential political strategy.

Pete Roussel, a White House deputy press secretary, said that Reagan, who celebrates his 71st birthday today, will be given "a synopsis" of his advisers' conclusions.

The meeting of the 16-member group came in the wake of surveys by Republican pollster Richard B. Wirthlin showing a decline in support for the president and for the GOP.

Camp David has been a favorite retreat for presidents in political difficulty. They have come off the Maryland mountaintop to announce new policies, new personnel and new themes. What made yesterday's meeting different from those of past presidencies is that the president wasn't there.

Those who were there comprised the core of Reagan's 1980 presidential campaign strategy group. Among the four advisers with no formal ties to the administration were Stuart Spencer, the top political adviser of that campaign, and Wirthlin, who doubled as Reagan's pollster and strategist. Another well-known Republican pollster, Robert Teeter, attended, as did Lyn Nofziger, who recently resigned as White House political adviser.

Most of the 12 White House advisers who attended also were prominent in the 1980 campaign. The list was headed by the "Big Three": White House chief of staff James A. Baker III, who presided at the session, deputy chief of staff Michael K. Deaver and White House counselor Edwin Meese III.

Others who made the trip to the presidential retreat north of Washington included trade representative William E. Brock, a former Republican national chairman; Ed Rollins, Nofziger's successor; deputy press secretary Larry Speakes; communications director David Gergen and White House aides Richard Darman, Craig Fuller, Rich Williamson, Joe Canzeri and Jim Jenkins.

Officially, the White House tried to dismiss the meeting as routine. In fact, several of those attending went with growing concerns about the public's perception of the president and the administration.

One adviser said that the White House wasn't taking adequate advantage of Reagan's communicative skills. Others expressed concern about the impact on the fall elections of the more than $90 billion budget deficit that Reagan will announce Monday.

The poll data that confronted the advisory group also were sobering, showing a steady decline in Reagan's support and a marked increase in skepticism about the effectiveness and fairness of his economic policies.

A kernel of good news: a large majority of Americans still believe that Reagan's policies should be given more time to work, a line likely to become a major part of the administration's political litany this year.

While his advisers were at Camp David, Reagan told a group of congressmen that his federalism program will produce "no winners and no losers." Budget director David A. Stockman said Thursday that it was impossible to be sure that no states would gain or lose from the program after 1987.

It was announced at yesterday's White House briefing, the first conducted by Roussel, that Edwin L. Harper, deputy director of the Office of Management and Budget, will replace Martin C. Anderson as assistant to the president for policy development. Anderson resigned this week, effective March 1. GRaphics1: Stuart Spencer...top advisor of 1980 campaign