ERIE, Penn. (Reuters) - Republican vice presidential candidate Sarah Palin on Thursday said Democratic nominee Barack Obama would be incapable of meeting U.S. national security challenges.

Palin, whose selection as Republican John McCain’s running mate prompted criticism of her scant national security experience, spoke after meeting a group of retired military commanders and the former leaders of the CIA and the Homeland Security Department.

“Barack Obama didn’t have much to say in that long infomercial of his last night about the stakes in the wars America is fighting, or about the need to support the troops in the field, or why he supported cutting off funding to our troops in the war,” Palin said.

Palin said Obama’s 30-minute television ad on Wednesday sought to wrap his “closing message” before the Nov. 4 election in warm and fuzzy commercial trappings.

“He wants to soften the focus in these closing days, hoping your mind won’t wander to the real challenges of national security that he is incapable of meeting,” said Palin.

Five days before the election, Obama leads in national polls and has campaigned hard on economic themes as the country faces its worst financial crisis since the Great Depression.

A New York Times/CBS poll published on Thursday, in which Obama led McCain by 11 percentage points, also found that 59 percent of respondents believed Palin was not prepared for the job of vice president, up 9 percentage points since the beginning of the month.

Nearly a third said the vice presidential choice would be a major factor influencing their vote for president.

BIDEN DEFENDS OBAMA’S JUDGMENT

Speaking in Allentown, Pennsylvania, Democratic vice presidential candidate Joe Biden lashed out at the McCain campaign’s attacks against Obama and said they were aimed at dividing the nation.

“I know Barack Obama ... this man has steel in his spine,” Biden said to roars of applause.

“In a dangerous world, you see Barack Obama exercise sound judgment about Iraq, about Afghanistan and about Korea while John McCain has demonstrated poor judgment,” Biden said.

“If you want to know where those (failed) policies are going to lead us, just look in the rearview mirror,” he added.

Palin said it was possible for the 47-year-old Obama, a first-term Illinois senator, to be “admirable in many ways” but he was not yet ready for the most important job in the world.

“Rousing speeches that can fill a stadium, perhaps cannot keep this country safe,” said Palin, who has revved up the conservative Republican base but failed to win over many more moderate and independent voters.

“For a season, a man can inspire with his words. But for a lifetime, John McCain has inspired with his heroic and trustworthy deeds. And in five days, it will all come down to a choice between these two men, Barack Obama and John McCain,” Palin said.

She made similar comments to a packed rally in Erie, drawing cheers when she said former Vietnam war prisoner and Navy pilot McCain understood the costs of war after commanding more than just a “scripted political campaign.”

The 72-year-old McCain has expressed confidence in Palin’s ability to handle any crisis, dismissing critics who say her two years as Alaska governor and earlier stint as a small town mayor were not enough to prepare her to become the country’s second in command.