Washington — How does Ronald Reagan take on Geraldine Ferraro? He goes after Walter Mondale. As Republican strategists assess a Democratic campaign revitalized by the vice-presidential candidacy of the congresswoman from Queens, N.Y., they are as uncertain of the effect of a woman candidate on voters as are the Democrats. They magnanimously call Ms. Ferraro an ''exciting addition'' to the ticket. But until they see how she performs and the extent of her appeal, they are bypassing her in favor of a ''tough and aggressive'' campaign focused on the Democratic presidential candidate.
''The more we go after her and the more we make her the issue, the more sympathy we create for her and the more credibility we give her,'' says Edward J. Rollins, director of the Reagan-Bush campaign committee.
Stuart Spencer, a key political adviser to the President, says that he has no assessment yet of Ms. Ferraro, that she has still to define her image, and that the GOP campaign will start evaluating her only in September.
Launching this sock-it-to-Mondale strategy in his press conference Tuesday night, President Reagan characterized the Democratic nominee as a big-spending liberal who would be soft on communism in Central America. Seizing on Mr. Mondale's declaration that taxes must be raised next year no matter who is president, Mr. Reagan vowed that he would not raise taxes if reelected. ''I have no plans for a tax increase,'' he declared, at the same time deftly leaving himself an opening if spending levels changed.
Not to be drawn into any negative comment about Ms. Ferraro, the President called the selection of a woman vice-presidential candidate ''long overdue.''
Continuing a feisty stance at a family rally in Austin, Texas, on Wednesday, the President assailed the Democrats for trying to bury the American dream in a ''graveyard of gloom and envy,'' ''endless tax increases,'' and ''deeper dependency.'' He also twitted them for choosing Representative Ferraro over Texas native son Lloyd Bentsen.
''Come where you will be welcome and appreciated,'' he told Texans in prepared remarks. ''The national Democratic leadership is going so far left, they've left America.''
If the GOP's present strategy is basically to address Mondale rather than Ms. Ferraro, that does not mean ignoring the blue-collar ethnic and Roman Catholic constituencies to which she would logically appeal or the themes that she and other Democrats struck at their get-together in San Francisco. Reaganites are especially sensitive to the fact that the Democrats are trying to preempt the issue of ''traditional values,'' and they are conspicuously promoting the President's conservative social agenda to appeal to middle-income families and hang on to the blue-collar and Catholic vote.
''We're going to go in and fight for the Catholic vote,'' Mr. Spencer told reporters, alluding to the President's planned visit today to a Catholic church in New Jersey.
Political commercials being televised nationally this week echo the President's challenge to Mondale to persuade the Democratic leadership of the House to act on six bottled-up legislative bills he supports.
Among them are measures calling for expanded individual retirement accounts (IRAs) for nonworking spouses, tuition-tax credits for parochial and other private-school students, an anticrime package, and legislation to permit the use of public-school facilities for student religious meetings.
Responding to the Democratic charge that his policies have hurt the poor, Reagan in his news conference Tuesday accused the Democrats of ''demagoguery.'' He also assailed their policy on Central America, suggesting that they would let El Salvador ''slowly bleed to death.''
It is clear that the Republicans intend to make this a highly ideological campaign by assailing the Democratic candidates as ''liberals,'' even though Mondale sought a middle-of-the-road position in his nomination-acceptance speech. Except for talking about traditional values and patriotism, Reagan strategists say, Mondale has not moved to the center.As for Ms. Ferraro, ''99 percent of the members of the House are to the right of her,'' Mr. Rollins says.
Democrats hope to capitalize on the ''gender gap'' with the Ferraro candidacy , but this is one of the uncertainties in the 1984 campaign.
Political analyst Richard Scammon notes that in presidential elections women have tended to vote Republican more than men and to shift from one party to the other less often than do men. Between 1976 and 1980, for example, there was almost no movement in the women's vote, while men swung appreciably from Jimmy Carter to Ronald Reagan.
With women and blacks playing a potentially larger role in this election, both political parties see voter registration as especially important.
While Democrats look to a massive turnout to put them over the top, Reagan political planners say the Democrats have a long way to go and that the Republicans have already registered 1.5 million new voters and expect to have 3 million by election day. In the GOP view, the new voters will probably break even between Democratic partisans and Reagan supporters.
Despite a Newsweek-Gallup poll this week showing Mondale with a two-point lead over the President, Reagan campaign officials say their own polls conducted after the Democratic convention show Reagan with a lead of 5 to 10 points in more than 40 states.
The industrial states, where there are heavily Democratic populations, are expected to be the toughest battleground. California and Florida are thought to be out of reach of the Democrats. Reagan is also strong in the West, stronger than anticipated in Texas, and doing well in the South, GOP campaign strategists say.