Hillary Clinton lends her fund-raising strength to Democratic Senate candidate Bob Casey Jr. today.

The afternoon event at Chicago's Palmer House Hilton, Clinton's first for Casey, is a sign of Pennsylvania's importance in the Democratic Party's bid this year to gain control of the Senate. Casey holds a comfortable lead over Sen. Rick Santorum (R., Pa.) in the polls, but the senator has a 2-1 fund-raising edge over his leading challenger. click here