The recent sharp exchanges between the Bush and Kerry campaigns over the war on terror and Iraq underscore the extent to which the election will probably come down to this: which candidate voters believe will do a better job at keeping America safe - and whether they view the Iraq war as contributing to or detracting from that effort.
Both sides are framing the debate primarily through the lens of character and temperament, rather than specific policy differences. The Kerry campaign portrays President Bush as reckless, saying he has alienated longstanding allies and led the nation to war without a plan to win the peace. The heart of the critique was encapsulated by former President Bill Clinton's assertion at the Democratic convention that "strength and wisdom are not opposing values."
The Bush campaign, for its part, casts Senator Kerry as indecisive and even weak. Earlier this week, Mr. Bush mocked Kerry for saying he would still have voted to authorize the Iraq war even knowing what he knows now - portraying it as a shift in position. Thursday, Vice President Dick Cheney attacked Kerry's claim that he would reach out to allies and fight a more "sensitive" war on terror. "America has been in too many wars for our wishes, but not a one of them was won by being sensitive," he told a crowd in Dayton, Ohio.
In part, the sparring reflects the fact that Kerry has been eroding Bush's lead on national security. Polls taken after the Democratic convention show that although Bush still holds an overall lead in fighting the war on terrorism, Kerry has moved ahead on the question of which candidate voters see as a stronger commander in chief.
Some of those shifts may have come in response to the findings of the 9/11 commission, which suggested the administration has not taken enough steps to protect the nation against the terrorist threat.
But much of the drag on the president's national-security ratings has come from Iraq. Public opinion has grown more negative on the war in recent weeks, with a majority of voters now saying it was not worth the human and financial cost. Yet a majority continues to support the original decision to invade - suggesting that the public remains more ambivalent than opposed.
Both campaigns are working to elevate one or the other of these competing strains of thought: Bush wants voters to focus more on the original decision to go to war and the overall goals the US has set out there. Kerry wants the focus to be on the execution of those goals.
The public's ambivalence is in many ways in line with the position Kerry has laid out - standing by his original vote to authorize the invasion, yet criticizing the way Bush has executed the war. All along, polls showed that most Americans wanted more multilateral support for the war, an area where Kerry has argued he would have more success.
Yet analysts say even if voters themselves are ambivalent about a policy, they still want leaders who come across as strong and decisive - an area where Bush still has an edge.
"When it comes to the positions [on Iraq], Kerry is more in line with the public," says Steven Kull, director of the Program on International Policy Attitudes at the University of Maryland. "However, Bush is perceived as having certain traits they like in leaders."
Still, by focusing on Bush's execution of the war, Kerry is making an argument about personal traits, too - one that analysts say is resonating. Even among some Republican voters, there's a concern "that [Bush] doesn't know what he's doing - that he's not wise, he's not careful," says John Mueller, an expert on war and public opinion at Ohio State University.
Overall, polls show the public remains divided on the issue of Iraq. Peter Feaver, a political scientist at Duke University in Durham, N.C., divides voters into four camps. At opposite ends of the spectrum lie the Bush base, which supports the decision to go to war and believes the US will win, and the "Vietnam syndrome crowd," which did not support the war and believes the US cannot win.
The battle is over the two camps in the middle: the "noble failure" group, which believes that the decision to invade was right, but that now the war cannot be won, and the "pottery barn" crowd, which did not support the invasion, but believes in the "you break it, you buy it" rule, and feels the US must now succeed.
Significantly, the "noble failures" tend to lean toward Bush, but could be swayed to Kerry if he can convince them he would do a better job at getting allies into Iraq, allowing US troops to come home. The "pottery barns" lean toward Kerry, but could be swayed by Bush if they feel he shows more resolve for finishing the job.