Washington ? A three-judge federal panel Monday suspended enforcement of its May 2 ruling that struck down or modified key provisions of the nation’s new campaign finance law, effectively restoring the law as the legal ground rules for political fund-raising until the Supreme Court decides if the measure is constitutional.

The decision negated the immediate effects of the panel’s earlier 1,600-page ruling that found several sections of the law known as McCain-Feingold to be unconstitutional. Most notably, the panel had struck down a provision that barred the national political parties from raising unlimited amounts of “soft money” in unregulated contributions from corporations, unions and wealthy individuals.

Now the soft money ban will remain in effect, at least for several months.

In a series of fractured 2-to-1 rulings on May 2, the panel also modified another provision of the law, banning outside groups from airing commercials that attack or support a political candidate at almost any time during an election cycle.

Under the decision to “stay,” or suspend, the earlier ruling, outside groups will be free to run such ads except during the closing weeks of a primary or general election campaign. Several groups indicated that they will move aggressively to do so.

Although Monday’s stay order clarified the political fund-raising ground rules for now, much uncertainty still hovers over the 2004 election year. The Supreme Court will decide which provisions of the law survive numerous constitutional challenges, but it has not set a timetable for considering the case. Lawyers familiar with the matter said their best guess was that the Supreme Court could rule by late this year or early next year, just as the 2004 presidential and congressional campaigns begin to intensify.

Until then, the McCain-Feingold law, named for its two main sponsors, Sens. John McCain, R-Ariz., and Russell Feingold, D-Wis., will govern campaign finance in federal elections.