"Staying the course is important,” Kerry said. “But staying the wrong course is not a sign of strength -- it is a mark of stubbornness, and it ultimately weakens this nation and the world."
Kerry lashed out at Bush's war in Iraq, saying the administration brashly chose military force over political diplomacy, alienating many U.S. allies and spurring a string of insurgencies more than a year after the initial campaign.
Kerry's address, delivered in the northwestern city of Seattle, Washington, came three days after Bush defended his own vision for Iraq in a speech pledging no early retreat from the country.
Bush is basing much of his reelection campaign on his national security credentials. After the terrorist attacks of 11 September 2001, Bush's approval ratings soared, with many Americans viewing him as a strong leader ready to take decisive steps in the war on terror.
But recent polls show that the president's approval ratings have sunk below 50 percent -- the worst since he took office more than three years ago.
The same polls show Kerry with approval ratings equal to Bush's, and sometimes higher.
Kerry yesterday sought to take advantage of Bush's weakening approval rates. He stressed his own determination to fight terror and Al-Qaeda, while arguing that Bush's unilateral approach on foreign policy has left the United States weaker rather than stronger.
"If President Bush does not secure new support from our allies, we will, once again, feel the consequences of a foreign policy that has divided the world instead of uniting it. Our troops will be in greater peril. The mission in Iraq will be harder to accomplish, if not impossible. And our country will be less secure," Kerry said.
Kerry also laid out what he called America's "new imperatives" in restoring stability to Iraq and making gains in the fight against terror.
He pledged that, if elected, he would seek to repair ties with traditional allies and shift foreign policy to emphasize diplomacy and intelligence over military might.
He also vowed to adapt the U.S. military to deal with unconventional enemies like Al-Qaeda, and to end American dependence on Middle Eastern oil.
Kerry's remarks, while made in the context of a presidential campaign, raise the question of how far a candidate can go in criticizing the incumbent at a time when U.S. forces are fighting overseas.
Alan Lichtman, a professor of American political history at American University in Washington, tells RFE/RL that anything a president does is open to fair criticism from anyone, especially a political rival.
"Certainly a challenger has an absolute right to challenge the policies followed by an administration in a time of war or in a time of peace. Certainly during the Vietnam War, critics -- both in [U.S. President] Lyndon Johnson's own [Democratic] party and in the Republican Party, and in independent groups -- fundamentally challenged the Vietnam policies followed by that administration," Lichtman said.
But Lichtman says any presidential challenge must be careful not to use a tactic that could directly interfere with the war effort.
In 1944, during the height of World War II, Lichtman recalls, Thomas Dewey was challenging incumbent Franklin Roosevelt for the presidency. He says Dewey was urged by some supporters to criticize Roosevelt for the lack of preparedness for the Japanese attack on Pearl Harbor in 1941.
Lichtman says the U.S. Army's chief of staff at the time, George Marshall, persuaded Dewey not to make that challenge, saying it would reveal that the United States had broken the secret Japanese military codes, an admission that would have hurt the Allied war effort.
Lichtman says, "While it was perfectly legitimate for Dewey to criticize the Roosevelt administration in its conduct of the war, he drew the line at criticism that would directly affect the safety of our troops and directly undermine the war effort."
Lichtman says Kerry's criticisms may hurt Bush's chances for reelection on 2 November, but so far they could in no way be interpreted as directly interfering with the war effort in Iraq.