(CNN) - Barack Obama is charging that rival John McCain doesn't have any new ideas and that's why the Arizona senator's campaign is focusing its energy on anti-Obama ads.
"You haven't heard a positive thing out of that campaign in a month. All they do is try to run me down," Obama said while campaigning Wednesday in Union, Missouri.
The accusation came the same day that the Obama campaign released an ad comparing McCain to President Bush, and the McCain campaign released one likening Obama to Britney Spears and Paris Hilton.
"Since they don't have any new ideas, the only strategy they've got in this election is to try to scare you about me," Obama said.
Obama said McCain and Republicans are trying to paint him as a candidate who is "too risky."
"Basically what they're saying to you is, 'We know we didn't do a good job, but he's too risky.' Well let me tell you something. When we are in such dire straits economically, when our foreign policy has gotten so messed up, what's the bigger risk: choosing change, or choosing to do the same things that got us into this mess in the first place?"
As McCain campaigned on Wednesday, he stressed his independence from Bush and highlighted times he's spoken against the administration.
"My independence hasn't always made me friends in Washington. I was not elected Ms. Congeniality in the United States Senate," he said at a town hall in Aurora, Colorado.
McCain praised Obama for his speaking abilities and success, but said "my concern with Sen. Obama is - that on issues big and small - what he says and what he does are often two different things."
McCain said Obama's solution is to raise taxes and promised that he would not do the same.