Asheville (US): Republican John McCain is threatening to take off the gloves in his second presidential debate with Democrat Barack Obama on Tuesday, hoping to pummel his way back into electoral contention.

With his poll numbers heading south and the US financial crisis playing to Obama's strengths, McCain needs a game-changing performance during the candidates prime-time clash in Nashville, Tennessee.

Heading into the second leg of the three-debate series, both campaigns have been trading low blows with the November 4 election now less than a month away.

On Saturday, McCain's running mate Sarah Palin accused Obama of "palling around with terrorists," in an exaggerated reference to the Democrat's ties in Chicago to a former 1960s radical, university professor William Ayers.

Obama meanwhile alleged McCain's health care policies would deprive 20 million more Americans of life-saving insurance coverage, as he ramped up his portrayal of the Republican as out of touch with voters financial hardship.

Both charges were furiously denied by the other side and fireworks are possible at Tuesday s debate, especially given McCain s strategy of turning the election into a referendum on Obama s fitness to lead.

The strategy carries risks, however, as shown in the first debate on September 26 when independent voters told pollsters they felt turned off by McCain's combative demeanor and his pointed refusal to look Obama in the eye.

"The key thing will be whether McCain can get under Obama's skin this time. Obama was cool, maybe too cool, in the first debate," Dartmouth College professor of government Linda Fowler said.

Source : PTI