Washington — Back from a successful European trip and exuding cheerful self-confidence, President Reagan begins to look down the road to the November election - and a gradual step-up in his visibility on the political circuit.
For the past few months, while the Democrats have been sparring, Mr. Reagan has occupied the high ground of ''acting presidential,'' letting the Democratic squabbling dominate the news. At the same time, the President has been using the powerful ''bully pulpit'' of his office to send out the positive messages of conciliation abroad and strength at home which American voters are presumed to want to hear:
* The United States seeks to improve relations with the Soviet Union and is prepared for a genuine negotiation on nuclear arms reduction, once the Soviets decide to return to the bargaining table.
* Interest rates will begin moving downward by year's end and the robust economic recovery will slow somewhat but continue into 1985.
As the Democrats struggle to unite their party before the July convention, Republican political strategists now are gearing up for a new phase of the presidential reelection campaign - intensified preparations for taking on the Democrats in a more frontal way. GOP operatives already are opening up a bit in commenting on the Democratic race.
But the pace will be measured. ''We're still not going to be as visible and vocal as the Democratic camp will be,'' says John Buckley, deputy press secretary of the Reagan-Bush campaign committee. ''But things are moving ahead with every week - voter registration, party organization, the media campaign, and preparations for the general election.''
To get the electioneering going in earnest, California consultant Stuart K. Spencer is scheduled to arrive in Washington in mid-June to join the group of eight or so at the Reagan-Bush committee and the White House who have been guiding the reelection campaign. A close friend of the President, Mr. Spencer has planned Reagan's campaigns since the gubernatorial days and is regarded as the key figure in Reagan strategy and style. Drew Lewis, former transportation secretary, will also join the campaign after the GOP convention in August.
Mr. Reagan will make at least several campaign-funded political trips in the six weeks remaining before the Democratic convention, according to campaign and White House aides. In the next three weeks, he is also scheduled to make three or four non-campaign trips, primarily to the Northeast. The President will travel in July to Los Angeles to open the Olympic Games, a forum that will give him good visibility.
Then, after the Republican convention in Dallas in August - around Labor Day - Reagan will begin campaigning seriously, making at least a couple of trips a week.
An avid campaigner, the President is described as ''very anxious'' to get out on the hustings. And although his aides indicate a desire not to overtire him, his campaign is expected to be a vigorous one.
Anticipating that Walter Mondale will be the Democratic candidate, campaign planners say they expect to focus largely on Mr. Reagan's record of accomplishment in the White House: a ''strong leadership'' that has restored the economy and built up the nation's defense. With a view to courting the independent vote, say GOP operatives, the President will have to point out his independence from special interests and the fact that there has been a ''tremendous change in the political agenda and direction for the future.''
Contrasts will be drawn with the Carter administration, of which Vice-President Mondale was a part. ''Even if Mondale were not the candidate, we have to point out how bad things were under the previous administration and under the control of both houses (of Congress) by Democrats, and how much things have changed for the better,'' Mr. Buckley says.
Talking about second-term presidential plans poses a more sensitive task for Reagan political planners. The Democratic candidate is certain to challenge the President on such issues as the huge budget deficit.
But if Reagan is too specific in outlining steps to resolve the budget dilemma, he risks alienating voting blocs, such as social security recipients who are concerned that their benefits may be endangered by reform of the system.
Nonetheless, Reagan cannot escape giving voters some sense of the future, GOP operatives say. And he is expected to talk in broad terms about such initiatives as reform of the tax system, promotion of enterprise zones (a Reagan initiative all but forgotten in this term), and a subminimum wage for youth, along with emphasizing continuity of first-term policies.
''It will be a forward-looking campaign, not just a status quo campaign,'' says Buckley.
Reagan campaign officials say that, organizationally, the campaign effort is going well. The Reagan-Bush committee has raised about $16 million and has received $10.1 million in federal matching funds; it has about $8 million left to spend in the preconvention season.
About 500,000 new voters sympathetic to Reagan have been registered as a result of an $8 million Republican registration drive. Surrogates are out giving speeches. A Madison Avenue advertising organization is in place and the first batch of commercial ads are being aired over television.
At the moment the GOP election mood is upbeat, with the President continuing to register high approval ratings. If the election were held today, say polls, Reagan would defeat Mondale or Sen. Gary Hart of Colorado.
But it is not ruled out that unexpected foreign policy or domestic developments could cast a pall over the campaign.
The Persian Gulf with its escalating war, for example, is one foreign trouble spot that could cause problems for Reagan, say campaign aides. So could a surge in interest rates and fresh revelations in ''Debategate'' - the obtaining and alleged use of Carter papers in the 1980 presidential campaign.
Also, Republican strategists are conscious of the fact that the Democratic campaign, too, is moving into a new phase.
Mondale, looking to wrap up the Democratic presidential nomination, is expected to shift his focus to assailing the Reagan administration and policies.
''Mondale is battle-sharpened now and therefore a better candidate,'' says a Reagan campaign consultant. ''He's a good campaigner and we can't underestimate him.''