WASHINGTON -- The Super Tuesday primaries have transformed the campaign for the Democratic presidential nomination. The central question suddenly has become whether Gov. Bill Clinton of Arkansas can be stopped.
Mr. Clinton's sweep of the Southern primaries has given him an impressive lead over former Sen. Paul E. Tsongas of Massachusetts in both delegate counts and the atmospherics of the campaign.
Mr. Tsongas and his partisans may argue that these were regional successes achieved by Mr. Clinton principally in states that border on his own. But Mr. Clinton's comfortable margin in Florida, the one Southern state in which Mr. Tsongas made a serious effort, cuts much of the ground from under that interpretation -- to the point that some professionals believe the Tsongas campaign made a strategic error in appearing to compete so heavily.
It is also true, however, that Mr. Clinton still is far from his goal of the 2,145 delegates needed to be assured of the nomination at the party's national convention in New York in July. Meanwhile, he has two questions to answer.
The first is whether he can win outside the South, something he has not yet done except in Wyoming. The opportunity lies just ahead in primaries next Tuesday in Illinois and Michigan, the first two Midwest industrial states on the Democratic schedule. In both states, opinion polls conducted before Super Tuesday showed Mr. Clinton leading Mr. Tsongas, although not by insurmountable margins.
The second question -- and this may never be answered -- is whether the Arkansas governor is a "safe" candidate for the Democrats to run against President Bush in the general election campaign in November.
Even as they were supporting him, some Southern Democratic leaders were privately telling reporters they feared "another shoe" would drop -- meaning another disclosure about Mr. Clinton's past that would cause controversies such as those that developed from Gennifer Flowers and from the issue of Mr. Clinton's history in avoiding the draft during the Vietnam War.
There is likely to be more than enough time and opportunity to deal with both of these questions about the Arkansas Democrat before he accumulates 2,145 delegates, if he does. The Democrats have built into their system almost 18 percent of the delegates who are chosen as officially unpledged, including just under 400 members of the Democratic National Committee and 245 members of the House of Representatives.
Some of the DNC members, largely in the South, already have indicated a preference for Mr. Clinton. But they are not legally locked in to their position. Neither are other delegates elected as "uncommitted" or as supporters of two prior candidates, Sens. Bob Kerrey of Nebraska and Tom Harkin of Iowa.
But the first rule of politics is that you can't beat somebody with nobody. And what that means in this case is that Mr. Tsongas is under far greater pressure than ever to win one of the two Rust Belt states next Tuesday. Without such a turnaround, Mr. Clinton would be well placed to persuade the uncommitted and other party leaders that the train is leaving the station.
On the other hand, the change in the pace of the primary schedule gives Mr. Tsongas -- and the party -- time to consider before anointing Mr. Clinton. After the tests in Illinois and Michigan, there are no major states with big prizes on the ballot until New York April 7 and Pennsylvania two weeks later.
If Mr. Tsongas is able to project himself as a continuing credible alternative, it is unlikely Mr. Clinton could lock up the nomination before the end of April and perhaps not until the late primaries in Ohio in May and California and New Jersey on the final primary day June 2.
The history of recent Democratic nominating contests also suggests there is still the possibility of sharp turns in the road. In 1984, for example, former Vice President Walter F. Mondale seemed to be sailing toward the nomination only to lose to Gary Hart in Ohio and in several late primaries in the West, including California.
The difference here is that Mr. Tsongas has not yet persuaded the political community -- including many of the uncommitted delegates -- that he is a plausible alternative to Mr. Clinton.