John Kerry (search) said Wednesday that terrorists have gained new havens and "extremism has gained momentum" in Iraq because President Bush has mishandled virtually every step of the war.

"Our differences could not be plainer, and I have set them out consistently," the Democratic presidential candidate told veterans at the American Legion (search) national convention. "When it comes to Iraq, it's not that I would have done one thing differently, I would have done everything differently."

Kerry delivered his critical assessment of the administration's performance in Iraq as the GOP mustered in New York City to nominate Bush to a second term. Challengers typically refrain from major campaigning during the other party's nominating convention.

Kerry, a decorated Vietnam veteran and Legionnaire, said Bush's actions before and after U.S. military operations have failed to make Iraq a safe and stable place.

"Today, terrorists have secured havens in Iraq that were not there before, and we have been forced to reach accommodation with those who have repeatedly attacked our troops," he said. "Violence has spread in Iraq, Iran has expanded its influence, and extremism has gained momentum."

Despite those conclusions, Kerry said he believed the war against terrorism could be won. "With the right policies, this is a war we can win, this is a war we must win and this is a war we will win," Kerry said.

Bush had delivered the same message to an audience at the same convention, reversing a statement he had made in an interview earlier when he said he doubted the war could be won.

The Bush-Cheney campaign challenged Kerry's statement that he's had consistent principles on the war against terror.

"This is a candidate who voted for the war, voted against the troops and said he was an anti-war candidate, and then said he would make the same vote for the war again," said Bush spokesman Steve Schmidt. "The only way to keep track of his position on Iraq is to follow which position benefits him politically."

Kerry ticked off a list of what he sees as Bush's missteps and mistakes in Iraq and Afghanistan — and included a reminder that the terrorist leader implicated in the Sept. 11 attacks, Osama bin Laden, remains at large.

"I would have sent the best trained forces in the world to get the No. 1 criminal in the world," he said.

Kerry also said he would have given inspectors more time to search for nuclear, biological and chemical weapons in Iraq, listened to the advice of senior military and diplomatic advisers, sent American troops to battle with better equipment and asked more foreign nations to shoulder the military and financial burden.

Kerry told the veterans that he would do more than Bush to ensure that returning soldiers have access to health care and would improve benefits for veterans wounded in battle. He said veterans also need a secure, growing economy with plentiful jobs when they return home from duty.