Palin, governor of Alaska and running mate of Republican U.S. presidential nominee John McCain, Saturday accused Obama, a U.S. senator from Illinois and McCain's Democratic opponent, of associating "with terrorists who targeted our own country."
It was an apparent reference to Obama's dealings with University of Illinois at Chicago Professor William Ayers, who in 1969 co-founded the militant anti-Vietnam War group Weather Underground.
Obama campaign spokesman Hari Sevugan told CNN Palin's comments were "offensive" and "not surprising" given the McCain campaign's statement that "they would be launching Swift Boat-like attacks in hopes of deflecting attention from the nation's economic ills."
CNN said its own investigation of Obama's links to Ayers found they were confined to the two men working together on a non-profit group to raise funds for a Chicago school improvement project and a charitable foundation, adding there was nothing to suggest anything inappropriate.
"What's clear is that John McCain and Sarah Palin would rather spend their time tearing down Barack Obama than laying out a plan to build up our economy," Sevugan told CNN.