WASHINGTON -- Despite all of the political obstacles Republicans may face in this troubled election year, Barack Obama has some big problems of his own.

At a time when the GOP is swimming upstream against a slowing U.S. economy, an unpopular war and a damaged party brand, the freshman senator is showing signs of weakness in the polls amid growing questions about his inexperience and his inability to respond boldly to a national-security crisis.

Heading into the final week before his nominating convention, major polls showed him slipping in the national numbers and in a number of battleground states where he had once led but is now in a dead heat against John McCain.

The latest Pew Research Center poll reported that "Obama's lead over John McCain has disappeared." Obama had a 3-point edge (46 percent to 43 percent) compared to the 8-point margin he enjoyed in June. Other polls showed a tie or a statistical dead heat. The Gallup daily tracking poll showed the two rivals at 44 percent each one day and a few points apart the next.

More troubling for Obama's candidacy, Pew showed McCain attracting more support from his party's base, including white evangelical Protestants (68 percent to 24 percent), as well as white working-class voters. He also leads overall among white voters and crushes Obama among Southern whites by 29 points (60 percent to 31 percent).

"An even greater percentage of voters than in June now see McCain as the candidate who would use the best judgment in a crisis, and an increasing percentage see him as the candidate who can get things done," Pew reported last week.

When Pew asked 2,414 registered voters, "Which candidate would use good judgment in a crisis?" 51 percent said McCain, and 36 percent said Obama -- a 15-point lead on a critical issue in a still dangerous world.

While the poll was conducted largely before Russia's military invasion of the Republic of Georgia, its findings strongly underscored the favorable reviews that defense analysts gave to McCain's response to that crisis.

"The Obama campaign's behavior during the Georgia crisis vindicated the suspicions of many that Obama is not up to speed on major international conflicts," said Ariel Cohen, a top foreign-policy analyst at the Heritage Foundation.

"His campaign was vague and slow to react in (its) response to the Russian invasion. It's clear that Obama is within the mainstream of Berkeley, Calif., in terms of the security and defense issues that concern American voters," Cohen told me.

"I think voters are aware of the candidates' life stories and exposure to the crises, including McCain's career as a naval officer in time of war, and his work over many years in foreign-affairs issues that came before Congress, and have concluded that is better preparation to be a crisis manager than being a state senator in Illinois," he said.

But Obama's weakness runs deeper than this. Several weeks ago, he was running quite well in a number of Republican battleground states that Democrats have targeted for takeover this year. This week, McCain was either tied or had the edge in Colorado, Ohio, Virginia, Florida, Missouri and Nevada.

In Colorado, a state that has been trending Democratic, McCain has edged ahead by 3 points, according to a Rocky Mountain News poll. In Ohio, an economic basket case that Democrats swept in 2006, the Real Clear Politics Web site showed McCain with a slight edge in the pivotal state. Continued...