With less than a month to go, the US presidential race is growingly negative as both candidates questioned the other's character yesterday.

After Democratic presidential candidate Barack Obama was pummeled over the weekend for his alleged ties to a former radical organization founder Bill Ayers, a top Obama aide accused his Republican opponent John McCain of waging a "dishonest, despicable smear campaign."

At the same time, Obama went negative too, launching a documentary reminding voters that in the 1980s McCain was one of the "Keating 5," a group of lawmakers who were investigated for trying to fend off charges against a campaign contributor who was a major player in the savings and loan scandal.

McCain was later exonerated of wrongdoing, but criticized for "poor judgment."

The two candidates, who will be face to face at their second debate on Oct. 7, traded long distance personal shots today as the rhetoric heated up.

"My opponent has invited serious questioning by announcing a few weeks ago that he would 'take off the gloves,'" McCain told a rally in Albuquerque, N. M.

"Since then, whenever I have questioned his policies or his record, he has called me a liar," he added.

Earlier in the day, Obama got in his own personal dig about McCain.

"If McCain wants to have a character debate then I am happy to have that debate," Obama said on a radio show.

Obama was unapologetic about the raising of the Keating 5 issue and suggested it was in retaliation for the McCain camp raising the Ayers allegations.

"One of the things we've done during this campaign: We don't throw the first punch, but we'll throw the last," Obama said.