John McCain, the Republican standard-bearer for November's election, meanwhile won backing from President George W Bush for his demand to open the US coasts to offshore oil drilling at a time of sky-high fuel prices.

Barack Obama convened a new group of advisers on security policy that included prominent backers of his defeated primary rival Hillary Clinton, including former secretaries of state Madeleine Albright and Warren Christopher.

The Illinois senator also met with about 40 retired generals and admirals for an overview of the US armed forces, as he parried a second day's offensive from the McCain camp about his plans to fight Islamic extremism.

"I refuse to be lectured on national security by people who are responsible for the most disastrous set of foreign policy decisions in the recent history of the United States," Obama said on Wednesday after the security advisers' meeting.

"Because the record shows that George Bush and John McCain have been weak on terrorism. Their approach has failed. Because of their policies, we are less safe, less respected, and less able to lead the world," he said.

"It's time to turn the page," he said.

McCain supporters again lashed out at a call by Obama for suspected extremists to be prosecuted, in light of a Supreme Court ruling last week allowing Guantanamo Bay detainees to challenge their detention in US courts.

Source: By DDNEWS