With polls showing either President Obama or Mitt Romney with a narrow lead nationally, and close contests in key battleground states, both campaigns have expressed confidence ahead of the debate.

Romney has been in the Boston area practicing. President Obama spent a third and final day in Williamsburg, Virginia, immersed in preparations with advisers and campaign staff.

Officials describe him as "calm and energized," saying he is ready to make a passionate case that his policies will be better for middle class Americans than Romney's.

Both campaigns unleashed new ads.  An Obama ad featured supporters voicing confidence in his economic policies.  Romney ads used excerpts from the first presidential debate.

OBAMA AD:  "President Obama does get what people need and that is jobs and the opportunity to help themselves."   VOTER:  "Stick with this guy, he will move us forward."

ROMNEY AD:  "Look at the evidence of the last four years.  Under the president's policies, middle income Americans have been buried.  They have just been crushed."

Obama campaign officials declined to detail how the president's preparation has differed from the first debate, when Obama said he had a "bad night."

Brookings Institution analyst Stephen Hess says the president has a chance to recover from his poor performance in the first debate.

"The first [debate] is terribly important, that has been the history of these debates.  But there have been other situations, certainly an example of a comeback would have been Ronald Reagan in his second campaign when he was running against [Walter] Mondale and in which he did very poorly in his first debate and came back very strong in his second debate and of course overwhelmingly won that election," said Hess.

The campaigns are also focusing on key states like Ohio.  No Republican has ever won the presidency without winning Ohio.  Polls show President Obama holding on to a lead there.

His wife Michelle spoke in central Ohio on Monday about what she called her husband's conviction.  In neighboring Pennsylvania, Ann Romney said the last debate gave Americans an "unfiltered" picture of her husband.

ANN ROMNEY:  "They heard with their ears and they saw with their eyes and what did they see, they saw a man ready and prepared to lead this country."

MICHELLE OBAMA:  "What truly made me fall in love with my husband was his character and I mean that, it was his decency and his honesty, the same thing we see in him every single day as president, that compassion and conviction."

Tuesday's second debate will be a town hall format that analysts say will test the ability of both candidates to respond spontaneously to questions from the audience, with possible followups from the moderator.

Foreign policy will be the focus of a third and final debate next week in Florida.