Handicapping the Homestretch

The same working-class voters who provided Clinton with a win in Ohio are expected to propel her to victory in Pennsylvania, the biggest prize left, on April 22. Obama has downplayed the significance of the state and has spent much of his time campaigning elsewhere.

Indiana and North Carolina have more delegates between them than Pennsylvania. Obama is favored in North Carolina, where African Americans are expected to make up a sizable portion of the electorate, while Indiana is as much up for grabs as any state left to vote. The two states vote May 6.

Clinton has a huge advantage in West Virginia, which is made up almost entirely of working-class whites, but with only 39 delegates at stake on May 13, the small state is unlikely to reshape the race.

A split seems likely May 20, with voters in Oregon going for Obama and those in Kentucky siding with Clinton. But that could easily change this late in the primary season if either candidate is able to build momentum in preceding weeks.

Clinton has dominated among Hispanic voters stateside, and Puerto Rico is likely to continue that trend June 1 in a primary with 63 delegates at stake.

Obama's lead has been built in large part by winning among less populous, less Democratic electorates, and two such states -- South Dakota and Montana-- are likely to give the senator a two-state sweep on June 3, the final day of the primaries.