If this were a normal political year, the reluctance of Republican John McCain to consider running for vice president with Democrat John Kerry would be understandable. The right choice, in conventional terms, would be to stay safely within the Republican fold.

And if this were a normal political year, it would be acceptable for a Democratic activist such as Donna Brazile to dismiss a Kerry-McCain ticket as politically incorrect. "McCain has not been pro-choice; he's not been out front on affirmative action," complained Brazile, who managed Al Gore's presidential campaign in 2000. By the rules of politics as usual, she's right.

But this is not a normal political year, and it is emphatically not the time for politics as usual. The United States is in trouble. The country needs to pull together, across party lines, to handle one of its toughest tests since World War II.

The war in Iraq is unraveling, in ways that could harm America's interests for a generation. Every day brings new images of bloody disarray: more souvenirs of torture from Abu Ghraib; the severed head of an American civilian; the assassination of the president of Iraq's Governing Council; women and children killed by U.S. fire at what witnesses say was a wedding. Senior U.S. military officers are furious that their troops are being asked to pay the price for civilian mistakes.

America can't wait until November to resolve the uncertainty over Iraq. Too many lives are at stake. What's needed is a bipartisan signal that America will get it right -- staying the course but also working more closely with the international community and refocusing U.S. strategy on achievable goals.

The aftershocks of Iraq are dangerous because America is already bitterly divided at home. Red America and Blue America cohabit the same continent, but they seem to share little else. The widening chasm is clear listening to talk radio or watching cable television; I see it in hundreds of vituperative e-mail messages from Red and Blue partisans. The country seems to be entering a new era of bad feeling -- like the backbiting, second-guessing and cultural warfare that followed the Vietnam War.

I wish President Bush could find a way to reach out across party lines and be a unifier. He campaigned in 2000 as a leader who would heal America's partisan wounds. But in office he has too often done the opposite. No matter how much he invokes the unifying theme of the war on terrorism, he governs as an exclusionary conservative. And his vice president, Dick Cheney, seems to be running for the position of divider in chief.

I fear that Kerry by himself cannot bring Red and Blue America together, either. No matter how many times his campaign ads rerun footage of him in Vietnam fatigues, Kerry and the Democrats will remain on one side of the nation's ideological divide. Kerry's possible Democratic running mates are good men -- Dick Gephardt, John Edwards, Bob Graham, Bill Richardson. But they would not lift the Kerry campaign to a different level where party labels matter less than good sense.

Which brings me to John McCain. The Arizona Republican is a cranky, impulsive, headstrong man. But there is something of greatness about him. When he speaks in a Senate hearing, you listen in a different way -- knowing that this isn't the usual peacock politician but something else: a man whose will couldn't be broken even by North Vietnamese torturers.

McCain matters this year because he has come to symbolize bipartisanship. He broke with the Republican leadership years ago to push for campaign finance reform. He was early to question whether the administration's strategy for postwar Iraq was working. And he demanded accountability for abuse at Abu Ghraib by bluntly telling the secretary of defense, "No, Secretary Rumsfeld, in all due respect, you've got to answer this question."

Many Democrats would be furious at the thought that a Kerry-McCain "national unity" ticket might mean more pro-life judges; Republicans similarly would loathe any embrace of the party of Bill Clinton. But that's the point: This is an election in which both sides need to give up things that matter to them, for the sake of a country that matters more.

In normal times, people would accept McCain's response to joining Kerry: "I have totally ruled it out." But these aren't normal times, and McCain's response is unworthy. Simply put, the country needs him. The logic of a Kerry-McCain ticket isn't to win an election but to provide leadership for a divided country at war.

davidignatius@washpost.com