Hillary hopes for tidal change

But it is doable. More than 13 weeks remain before the last contest — the June 7 contest for Puerto Rico’s 63 delegates — and any number of game-changing gaffes, knockouts, debates, advertisements or world events could influence the race by then. To a large extent, the Clinton strategy is simply to run out the clock and hope — by dint of primary victories and her candidacy’s credibility — that she compiles the most delegates by then.

While Obama has enjoyed particular momentum recently in recruiting superdelegates — the party leaders who can pick a candidate themselves — Clinton advisers say they are urging the remaining 448 uncommitted superdelegates to sit tight and let the primary season play out before choosing a candidate.

It is unclear if they can succeed: the Obama campaign has been announcing each day that a new superdelegate or two have aligned with his efforts, and his advisers say they expect to continue recruiting more.

Unless they can freeze enough superdelegates in place, Clinton advisers acknowledge that the delegate arithmetic has them at a sharp disadvantage; Obama has 1,456.5 total delegates to Clinton’s 1,370. The remaining 12 primaries will award delegates proportionally to both the winner and the loser, meaning that future victories will not alter the delegate margins substantially. And it will be difficult if not impossible for either candidate to get the 2,025 delegates needed for the nomination, leaving the contest very likely in the hands of superdelegates.

Part of Clinton’s case to superdelegates is that they should at least wait and see her and Obama perform in the next big contest, the April 22 Pennsylvania primary, which awards 188 delegates. She is ahead in polls there, and enjoys support from Gov. Edward G. Rendell and several city officials.

A victory there, in turn, could give her good momentum heading into the Indiana primary two weeks later, her advisers say. The state’s influential Democratic senator, Evan Bayh, a former two-term governor, was one of Clinton’s earliest supporters. Indiana has 84 delegates.

The campaign advisers also believe that she has a shot in West Virginia, Kentucky and South Dakota, which have a combined 122 delegates, and that — given her strong support among Hispanics — she is likely to do very well in Puerto Rico, which has 63 delegates. But along the way are contests in North Carolina, where polls suggest Obama is well positioned, and Mississippi, which has a large black Democratic electorate.

Clinton advisers said Wednesday that they did not believe they had to open a significant new offensive against Obama to beat him in primaries or to freeze superdelegates in place. Rather, they argued that he was already on the defensive.

Noting that Clinton decisively won among voters who made up their minds in the days and hours before Tuesday’s vote, her advisers credited that momentum to her recent ads challenging Obama’s ability in a national security crisis, her campaign’s complaints about media bias favoring Obama, and questions about his financial ties to a former donor and friend who is on trial in Chicago on corruption charges. (Obama is not connected to the trial.)