McCain aims to stop Obama momentum in debate

By John Whitesides, Political Correspondent

NASHVILLE, Tennessee (Reuters) - Republican John McCain hopes to halt Democrat Barack Obama's momentum and gain new life in the White House race with a strong performance on Tuesday when the presidential rivals meet in their second debate.

With four weeks until the November 4 election, the debate offers McCain one of his last chances to recast a presidential race that has been shifting toward Obama in the last few weeks.

"McCain has a big opportunity with this debate," said Peter Brown, assistant director of the Quinnipiac University poll. "He has to change the dynamic and make people re-evaluate Obama."

The debate at Belmont University in Nashville, Tennessee, will begin at 9 p.m. EDT (0100 GMT on Wednesday).

Obama has solidified his national lead in polls and gained an edge in crucial battleground states as the Wall Street crisis has focused attention on the economy, an area where polls show voters prefer the Illinois senator's leadership.

A Reuters/C-SPAN/Zogby poll released on Tuesday gave Obama a 3-point edge on McCain, 48 percent to 45 percent, and other polls have shown a bigger margin for Obama.

The economic turmoil continued on Tuesday, with stocks tumbling for the second consecutive day in a sign the $700 billion bailout of U.S. financial institutions did not ease market concerns about the economy.

The Arizona senator's campaign has unleashed a volley of attacks on Obama in the last few days as his advisers signaled they wanted to turn the debate away from the economy.

McCain and running mate Sarah Palin have tried to turn the focus back to Obama and his associations with figures like former 1960s radical William Ayers and Obama's former minister, the Rev. Jeremiah Wright.

OBAMA COUNTERATTACK

That drew a counterattack from Obama, who raised questions about McCain's relationship with Charles Keating, a central figure in the U.S. savings and loan scandal in the late 1980s and early 1990s that cost taxpayers billions of dollars.

Each campaign released a new ad ahead of the debate, with the Obama campaign hitting McCain for wanting to "tear Barack Obama down" and the McCain camp accusing Obama of running misleading advertisements.

McCain's aggressive tone and Obama's sharp responses have raised expectations for an explosive debate, and Obama advisers said they are prepared for a hard-hitting approach by McCain.

"He has also signaled to his supporters that he is going to be very aggressive in this debate, that he is going to take the gloves off and so on," Obama adviser David Axelrod told reporters.

He said McCain was "desperately throwing left and rights hoping to win a knockout because he thinks he is behind."