Others are just plain suspicious of campaign promises.
Getting the attention of these "persuadable" voters is critical. A solid majority of voters have already made a firm decision on their Nov. 2 choice and just two in 10 say they are likely to switch to a different candidate.
That message never got to Democrat Debra Edwards, a 49-year-old homemaker from Lakemoor, Ill., who is leaning toward supporting Kerry.
"I didn't see the convention," said Edwards, who is busy raising grandchildren.
"I heard from a buddy, who was major, major impressed with Kerry's speech. I think Kerry's all right, but I don't care who they put in there. I just want Bush out," she said.
Only one-fifth of the public said before the convention they planned to watch a great deal of the event.
An estimated 24.4 million Americans watched Kerry's acceptance speech, according to Nielsen Media Research. That compares with 21 million people who watched Al Gore's speech in 2000.
Retired union electrician Doyle Moreland of San Antonio said Kerry did not overwhelm him.
"I watched the speech, I thought it was OK, but that's just talking," said Moreland, who leans toward supporting Kerry. "I don't care who they are, they're all going to say what they're going to do."
Some voters who preferred John Edwards beforehand said after the convention they were still happy with the choice.
But Democrat Terri Buchanan, a 36-year old bookkeeper from Tampa, Fla., said she has some doubts.
"Oh well ... he seems like another Dan Quayle," she said, referring to the Indiana senator who was George H.W. Bush's running mate in 1988. "He looks like he's too young to be in office."
One Republican voter who is not firmly committed to Bush said he watched the convention off and on.
"I'm still pondering," said Joel Potts, 34 of Monroe, Wis. "I'm just interested in hearing details of their different plans. If they were explaining how they're going to do these things, I missed that point."
A Newsweek poll released Saturday showed Kerry and Edwards leading Bush and Vice President Cheney 49 percent to 42 percent. Ralph Nader had 3 percent in the poll of 1,000 registered voters taken Thursday and Friday.
Bush's job approval was at 45 percent in the poll, and 53 percent said they would not like to see Bush re-elected.
Other polls in coming days will give a more complete picture of any surge for Democrats since the party convention in Boston. It sometimes takes several days after an event like the convention to pick up changes in public opinion.
Bill Clinton (search) got a 16-point boost after his convention in 1992, according to Gallup polling. Al Gore got an 8-point increase in his support. George McGovern got nothing in 1972.