The two presidential candidates, Republican John McCain and Democrat Barack Obama, are preparing to hold their second of three nationally televised debates in the southern city of Nashville. VOA Correspondent Cindy Saine reports from Washington the campaigns have sharpened their verbal attacks on each other.  

The debate will be in a town-hall style format, with questions coming from undecided voters, some in the live audience and others who sent their questions through e-mail. Veteran NBC television journalist Tom Brokaw will be moderating questions that he pre-screened.  

With Barack Obama holding a lead in public opinion polls and only 29 days left until the election, analysts say John McCain needs to do something dramatic to change the dynamics of the race.

During the past several days, McCain's campaign, led by vice presidential candidate Sarah Palin, has questioned Obama's values and his patriotism.  

CBS News analyst Jeff Greenfield said McCain clearly believes he needs to change the subject from the economic crisis.

"The McCain campaign has been remarkably candid in saying flatly, even on the record, we have got to change the topic from the economy, to raise doubts about Obama or we lose," he said.

McCain prefers town-hall style debates, and often seems energized by a live audience. But experts say such a format does not lend itself well to one candidate attacking another, for fear of being seen as too aggressive and too confrontational in the presence of voters.

Both McCain and Obama are widely considered to have delivered a strong performance in their first debate last month.  

Steve Thomma of McClatchy newspapers told MSNBC news that the candidates' style is important.

"Then there is the question of style," he said. "Who looks calm and reassuring, a sober hand in a time of crisis."

NBC's Mark Whitaker said voters are not likely to want to hear about the candidates' patriotism or past associations, but are more interested in hearing how each of them intends to fix the economy.

"The voters and the people in the audience who are going to be asking the questions, they are going to want to hear about the economy, they are going to want to hear about health care and so forth," he said.

Analysts say both candidates need to show voters that they understand the economic pressures they are facing. They need to offer some ideas on how they plan to lead the country out of the global economic crisis.