Republican candidate John McCain is hoping to reverse the dynamics of the race for the White House in his final presidential debate with Democratic candidate Barack Obama. Trailing in national polls and in key states, McCain will have another chance to try to win over independent and undecided voters, while Obama is hoping to avoid any costly mistakes. VOA Correspondent Cindy Saine reports from Washington.

Going into the debate at Hofstra University in Hempstead, New York, a new national poll by CBS News and the New York Times shows Barack Obama with a commanding 53-39 percent lead over John McCain. Other polls also show Obama ahead by a lesser margin. Wednesday night's debate is to focus entirely on the economy and other domestic issues. The two candidates will be seated at a table with veteran CBS moderator Bob Schieffer.  

Political analyst Larry Sabato of the University of Virginia says McCain faces a tough challenge in trying to stem the steady shift of voters towards Obama over the past couple of weeks.

John McCain addresses supporters in Montgomery County Community College in Blue Bell, Pennsylvania, 14 Oct 2008

"It's McCain's last opportunity to communicate with tens of millions of voters in an unfiltered way," Sabato said. "He has to do what he can, within the format of the debate, to add a new element to the election or change the direction of the election. That is asking a great deal under difficult circumstances."

McCain has taken a new approach this week, positioning himself as an underdog in the presidential race fighting for Americans facing tough economic times. He is reaching out to older Americans, with a new economic plan that calls for reducing the tax on early withdrawals from retirement accounts and cutting the tax rate on capital gains in half, among other measures. The current economic crisis has hurt McCain, as many voters blame his Republican Party, which has held the presidency for the last eight years.  

Melissa Wade, Executive Director of Debate at Emory University and an expert in debate training, says McCain needs to deliver a more even and steady performance than he did in the first two debates with Obama.

"McCain has appeared to be more erratic and less organized which has turned into a metaphor for some of the, I think, decisions made in his campaign," Wade said.

Barack Obama greets supporters in Maumee Bay Resort in Oregon, Ohio, 14 Oct 2008

Wade says Obama has appeared calm and presidential, and that he is much improved from his early days on the campaign trail during the Democratic primaries.

"At the end of the day he was calm, he was reasonable, he was steady," Wade noted. "This is a man who has learned in every date he has been in in the last year-and-a-half. He has gotten better each time. He was very rough when he first started. In every debate encounter he seems to learn something."

McCain has suggested that he may bring up Obama's association with Vietnam War-era radical William Ayers during the debate. His campaign is running a number of TV and radio ads attacking Obama for working on foundations with Ayers. But the latest CBS-New York Times poll suggests that many voters appear to be turned off by McCain's negative attacks. Twenty-one percent of voters say their opinion of McCain has grown worse over the last couple of weeks. Many analysts and debate experts also agree that it is risky for a candidate to launch personal attacks against an opponent in a face-to-face debate format.