The big drama now facing the Democratic Party in the presidential contest is how, when and even whether Senator Hillary Rodham Clinton will depart the race.
The contest is coming to a close as Puerto Rico votes on Sunday and Montana and South Dakota on Tuesday, finishing a process that began five months ago in Iowa. Even if those results do not put Senator Barack Obama over the top, aides to both Mr. Obama and Mrs. Clinton said they expected enough superdelegates to rally behind Mr. Obama in the 48 hours after the final primaries to allow him to proclaim himself the nominee.
In many ways, Mr. Obama is wheezing across the finish line after making a strong start: He has won only 6 of the 13 Democratic contests held since March 4, drawing 6.1 million votes, compared with 6.6 million for Mrs. Clinton.
Mrs. Clinton has kept her counsel about what she might do to draw her campaign to a close. But when the rules committee of the Democratic Party divided up delegates from Michigan and Florida on Saturday night, Harold Ickes, a committee member and Clinton adviser, said she was reserving the right to contest the decision into the summer.