Poll Predicts 111-Delegate Lead for Obama

A new poll by Thomas Riehle at RT Strategies indicates that Barack Obama's lead over Hillary Clinton in pledged delegates will be 111 after the polls in the Potomac primaries close tonight.

Obama's widening lead complicates the race in which Clinton is already seen as losing momentum.

"Once the lead is built, it is almost impossible for the trailing candidate to make up ground in a two person race," Riehle says. "The fact that Clinton has won all the big state primaries except Illinois proves pretty irrelevant in the face of that inexorable pledged delegate arithmetic."

While news organizations are in disagreement over delegate counts, Riehle argues that Obama has never trailed. On seven of the eight voting days in this campaign, Obama has won the largest number of pledged delegates, apportioned according to complicated delegate apportionment rules. On the other one — the day of New Hampshire's primary — the candidates tied.

—Bret Schulte