Shivering in blankets of Penn State's colors, some 20,000 people filled a campus lawn Sunday to hear Barack Obama say he can win the Democratic nomination even if rival Hillary Rodham Clinton stays in the race.

Obama's rally drew an estimated 20,000 to 22,000 people, according to university official Richard DiEugenio — by far the biggest in a weekend of smaller, face-to-face campaign stops since Obama launched a six-day bus tour through the state on Friday.

Supporters stood in long lines for hours to hear Obama ahead of the April 22 Pennsylvania primary.