Washington — After four months in office, President Reagan sits firmly in the saddle. In fact, there is much evidence, observers seem to be concluding, that he is presiding over what may later be described as a new "era of good feeling" in America.
The public perception of the President:
* He is both persistent and steady, marching purposely toward providing solutions for the economy.
* He is a man of courage -- a quality that came through vividly during and after the assassination attempt.
* His constant good humor and cheerfulness may be rubbing off onto the electorate, giving an optimistic tinge to their opinions of what lies ahead.
The assessments of political observers here and around the United States give Mr. Reagan a high rating for his performance thus far while noting that his presidency has had some reverses and underscoring that many possible pitfalls lie ahead.
Above all, these assessors find a public mood of satisfaction with the President, a widespread feeling that he is providing leadership even though this view is often mixed with unhappiness over some of his tax and social-security proposals.
The public is expressing what pollsters and reporters see as a decided shift in attitude since the November election. The same voters who were anxious for a change in the White House remain relatively tranquil, apparently pleased with the direction Reagan is taking on the economy and on foreign affairs -- or at least still willing to give him time to test his policies and programs.
There are, in fact, strong signs the public is so attuned to Reagan that it may well be that the conservative trend, evidenced at election time, is sweeping forward.
Polls are showing that the Republican Party affiliation is growing rapidly --while those who identify themselves as Democrats are declining.
The latest AP-NBC poll comes up with this startling finding: More Americans now say they will vote for Republican candidates for the House of Representatives than for Democratic contenders.
If this is so -- and if it holds true through the fall of 1982 -- then Reagan is likely to have a Republican-controlled Congress to work with during the last half of his term.
There are, however, some indications that the Reagan honeymoon is ebbing, perhaps moving toward an end.
Certainly when the Republican-controlled Senate rejected, by a vote of 96 to 0, the essential part of his social security program. It had to jar the President and his people more than a little.
In fact, the small firestorm of protest that followed Reagan's social security proposal, particularly his plan to encourage workers to stay on the job beyond age 62, has to be viewed as a decided political setback, if only a temporary one.
The President moved fast to indicate to both Congress and the people that all elements in his social security proposal were "negotiable." Thus the political damage may largely have been contained.
But there are many signs of possible trouble ahead that could send this President into a tailspin: in the Middle East, in relations with the Soviet Union, and, at home, in what happens to the economy, particularly inflation.
But, at four months, the Reagan "honeymoon" isn't over yet.