"It will be much sooner, right after the public has voted," Pelosi said.
Superdelegate Bob Mulholland, a Democratic National Committee member, also expects that the nominee will be decided well before the party's August convention in Denver.
"People ought to just relax," Mulholland said. "Whoever is ahead by 50 delegates or so, you'll see the super delegates move that direction. It'll just happen naturally."
Mulholland has not committed to either Clinton or Obama.
In her speech, Pelosi told state Democratic activists that they cannot let the hotly contested primary between Clinton and Obama affect their efforts in the November election against Republican John McCain.
"We have two great candidates for the President of the United States. At the end of the day our target, our eye on the prize, must be November," Pelosi said. "We must unite after this primary is over. I hope that will be before too long."
The convention lasts through Sunday. Former President Bill Clinton is scheduled to address the convention on Sunday morning.