The presidential spotlight shifts to the running mates tonight, amid signs that Sarah Palin's star is fading.

The latest national poll by the Pew Research Center for the People & the Press finds a majority of Americans, 51%, now believe Palin is not qualified to be President. That's up from 39% shortly after the GOP convention.

Although Palin provided a huge jolt of energy to the Republican ticket when she was first chosen, doubts about her readiness have mounted in recent weeks, especially after a stumbling interview with CBS's Katie Couric, and a withering parody on NBC's "Saturday Night Live."

The Alaska Governor still enjoys strong support among social conservatives. "She's got guts. She's got experience. She's really an impressive woman," said Selena Heyer, a stay-at-home mother of four with another child on the way. Heyer brought her son Ambrose to a McCain-Palin rally in Columbus, OH this week.

But Palin is not proving the draw for independent women that John McCain and his aides had hoped. According to the Pew poll, Palin has lost more ground with women since early September than she has with men. The percentage of women saying Palin is qualified to be President has slipped 18 points, while the drop among men is 12 points. (63% of Americans believe Joe Biden is qualified to be President. His favorability ratings have held fairly steady since early September.)

John McCain is courting female voters today, with a "Women's Town Hall Meeting" in Denver.