The leading U.S. presidential contenders have criticized each other's political tactics.

The campaign of Republican presidential candidate John McCain Thursday accused rival Democrat Barack Obama of playing racial politics.  In a statement, it accuses Obama, who is African-American, of using tactics that are "divisive, negative, shameful and wrong."

The accusation is in response to Obama's comments Wednesday in which he accused the McCain campaign of portraying him as a risky candidate because he is "new, and does not look like the other presidents on the currency."  All U.S. presidents have been white males.

In Cedar Rapids, Iowa, Obama alleged McCain has resorted to "predictable political attacks."  He cited as an example a McCain television ad that featured video of Obama's recent trip to Europe, mixed with images of American celebrities Britney Spears and Paris Hilton.  The voiceover in the ad says: "He is the biggest celebrity in the world, but is he ready to lead?"

Both candidates also discussed their energy policies on the campaign trail today.

Obama vowed to give Americans an energy rebate, crackdown on speculators who manipulate the market, increase domestic production and invest in renewable energy.

During a campaign stop in Racine, Wisconsin, McCain vowed to increase domestic oil drilling and further develop existing energy sources, such as nuclear power and clean coal.