John McCain and Sarah Palin plan to return to familiar criticism of Barack Obama's friends and supporters, just hours after a presidential debate that steered clear of the subject.

The Republican candidates planned joint appearances in key states of Pennsylvania and Ohio on Wednesday. Ahead of their appearances, the GOP ticket has released an ad that criticizes the Illinois senator as simply not presidential.

During Tuesday's debate, McCain did not criticize his rival's connection to 1960s-era radical William Ayers. The two are not close, but Palin has repeatedly faulted Obama for serving on non-profit groups' boards with a man whose Weather Underground group bombed the U.S. Capitol and Pentagon.

Meanwhile, Democratic vice presidential candidate Joe Biden said Wednesday that Republican rival Sarah Palin is injecting fear and loathing into their campaign with her criticism that Barack Obama is friends with a terrorist. He called the effort "mildly dangerous."

Palin began last weekend telling supporters that Obama is close to '60s-era radical William Ayers, a founder of the violent group the Weather Underground. After first claiming that Obama had been "palling around with terrorists," she changed the thrust of the attack to say that Obama's ties to Ayers showed bad judgment.

Obama and Ayers, now a college professor, live in the same Chicago neighborhood and have served together on community boards. The Illinois senator, who was a young child when the Weathermen were planting bombs in protest of the Vietnam War, has denounced Ayers' radical views and actions. His campaign has said that Obama didn't know of Ayers' past when they first met.

In Florida on Monday, Palin's remarks about Obama and Ayers elicited waves of booing from supporters. One person at a rally shouted "Kill him!" according to a Washington Post report. A sheriff who introduced Palin at a rally referred to the Democratic candidate as "Barack Hussein Obama."

Biden, appearing Wednesday on CBS' "The Early Show," called Palin's remarks about Obama and Ayers "over the top."