ST. LOUIS (AP) — The stakes were sky-high for Sarah Palin, not to mention Republican presidential candidate John McCain, as she debated Democrat Joe Biden Thursday night amid falling poll numbers and growing voter skepticism.

The Republican governor of Alaska faced off against the Democratic senator from Delaware in the most-anticipated vice presidential debate ever as surveys showed Barack Obama and Biden in a strengthening position for the Nov. 4 election.

The powerful boost McCain got from choosing Palin as his running mate is fading fast, and they looked to the debate at Washington University in St. Louis as a chance to restore some of that luster.

McCain mentioned the evening’s debate as he took the stage for a town hall meeting with several hundred women voters in Denver and was rewarded with a standing ovation and loud cheers.

“I know she’d be pleased at that incredible response, that frankly she’s inspired all over this country,” he said.

However, Palin is coming off a series of television interviews in which she has sometimes seemed to struggle.

The Obama campaign was eager to increase expectations for Palin, hoping they would then be dashed.

“She’s an extremely good debater,” Obama campaign manager David Plouffe told reporters aboard Biden’s plane Thursday afternoon. “We expect that she’ll have very witty, biting lines that she’ll get off tonight.”

While Plain is under pressure to present herself as a lucid and agile performer, Biden, too, must avoid the kind of extemporaneous remarks that have landed him in trouble before.

In preparing for the debate, Palin has secluded herself in McCain’s compound in Sedona, Ariz. Biden has been practicing in a hotel in downtown Wilmington, Del.

Palin’s rapid emergence as a political star and the attention both running mates have received for mistakes and for straying from their campaign messages was likely to attract an enormous television audience — eager to hear their views as well as perhaps see one of them slip.

The McCain campaign posted a video on its Web site Thursday morning drawing attention to past Biden misstatements.

The high stakes have also cast the spotlight on the debate’s moderator, PBS anchor Gwen Ifill. Some conservatives have criticized the Presidential Debates Commission’s selection of Ifill because she is writing a book, “The Breakthrough: Politics and Race in the Age of Obama.” The book is about how politics among blacks have changed since the civil rights era. She has said she has yet to write the chapter on Obama and has questioned why people think it will be favorable toward the Democrat.

“Frankly, I wish they had picked a moderator that isn’t writing a book favorable to Barack Obama,” McCain told Fox News on Thursday. “But I have to have confidence that Gwen Ifill will treat this as a professional journalist that she is.”

Plouffe, dismissed the complaints as “another in a long line of manufactured controversies.”