"A lot of our fellow citizens are justifiably concerned about Iraq. But what the enemy doesn't understand about this administration and millions of Americans is we're not going to run, " he said during a campaign in Greeley, Colorado.

"Iraq is vital to our security. Iraq is the central front in this war on terror. But I've been listening for the Democrats' plan for success. There's national silence. They have no plan for victory," Bush said.

The United States is to hold legislative elections on Nov. 7 and the Iraq war has become a key issue between the Democrats and the Republicans.

Opinion polls have found that a majority of Americans disapprove the way that the Bush administration is handling the Iraq conflict and Bush's approval rating has slipped to 35 percent.