Aug. 27 (Bloomberg) — "We listened to our hopes, instead of fears." With that line in Denver, Michelle Obama summarized it all. In America, politics isn't a contest between political parties. It is a contest between hope and fear. The party that has the hope usually gets the White House.

Right now, the Obama campaign is managing to evoke not just one hope but many different sorts from victorious presidential campaigns past.

Kennedy hope is the first kind that Senator Barack Obama and wife Michelle bring to mind. That's the hope of youth for upward mobility. Here the Obamas out-Kennedy both the Kennedys and Clintons.

Even though he was the first Catholic president, John F. Kennedy was the son of the ambassador to the Court of St. James. The path that Barack Obama climbed was a lot steeper, even if his parents were graduate students.

Starker yet is the contrast between Jacqueline Bouvier of Newport and Michelle Robinson of Chicago's South Side. The Robinson family's telling of their story of multiple sclerosis and the Brady Bunch was the most compelling in many a convention.

What mattered wasn't only that Michelle began her life humbly but that she didn't seem in the least angry about it.

Bill Clinton was literally the Man from Hope, and he wore the Kennedy mantle everywhere (recall that picture of him as a Southern teen shaking JFK's hand). Yet Clinton came off not as Kennedy but as Kennedy Canned. And, for her part, even in 1992, Hillary Clinton was more strident than the genuinely likeable Michelle. Whatever book the Obama chroniclers pen of 2008, it won't be satire like Joe Klein's "Primary Colors."

Recalling Reagan

Obama also kindles hope in the fashion of another president — Ronald Reagan in 1980. This has much to do with an accident of the business cycle — Obama is campaigning, as Reagan did, amid economic trouble. Obama's change message is a powerful update of Reagan's "morning in America."

President George W. Bush and the Republicans in Congress are supplying Obama with the backdrop by signing off on legislative remedies to the credit crunch that differ little from what the Clinton administration might have offered.

Here Republicans are casualties of their own success. One reason the last downturn was so mild was that the Grand Old Party courageously battled for lower taxes when the economy was fragile. The outcome helped Bush win re-election, only to become associated with the next downturn. It's probable the 2001 recession would have been worse had the Republicans followed Democratic advice. But that argument has the shadowy aspect of the hypothetical.

Nixon, Biden

"Hope" and "Richard Nixon" don't usually go together in the same sentence. Yet it is also Nixonian hope that the Obama campaign is evoking with its choice of Senator Joseph Biden for vice president. Nixon, like Obama, ran for president half a decade into an unpopular war. Nixon offered the hope of sane management of that war at a time when the sitting president, Lyndon Johnson, seemed to be abdicating.

In August 1968, Nixon said: "I believe there must be a negotiated settlement. I do not think that you are going to get a negotiated settlement unless you have the strong military and economic and political presence and policy that will encourage the enemy to negotiate."

Working on Bush

Biden is, like Nixon, a strong foreign policy veteran with an interventionist record and the goal of negotiating a strong peace. Like Nixon, Obama and Biden are focusing their criticism of the incumbent and his messy war, as much as on any plan of their own. As far back as 2004, Biden spoke at the Council on Foreign Relations, where I work, emphasizing his efforts to persuade a recalcitrant Bush to work harder on international cooperation: "I have met personally with the president. I have met literally for several hours with the president."

Senator John McCain, by contrast, stands for the old war. Many of us hope, with much justification, that the surge of American troops into Iraq that McCain endorsed will improve the long-term prospects in the Middle East. But the Democrats are betting that Americans see an exit strategy as the more desirable form of hope.

So Democratic claims to hope are both genuine and stagecraft. Together, they leave candidate McCain with little to campaign on but fear. McCain has a chance to win, people say — if the Georgian war expands or Iranian missiles generate an October Surprise.

That is hardly a powerful endorsement. Some conservatives are doing their own bit to limit McCain's prospects by attacking Obama even when he's right.

Chance for Substance

McCain's big chance to make his own call for hope comes next week, when the Republicans hold their convention in Minnesota. His opportunity is to offer substance to demonstrate that his hopes are more realistic: substance on Iraq, substance on banks, substance on economics.

After all, the most auspicious future for the U.S. lies in the relative competitiveness of the U.S. economy, not tax increases from Obama or House Speaker Nancy Pelosi.

Or Minneapolis may resemble the Boston of the Democrats' of 2004, a collective roar of rage a la Howard Dean. Then September, not November, may be the point at which Republicans definitively lose hope.

(Amity Shlaes, a senior fellow in economic history at the Council on Foreign Relations is a Bloomberg News columnist. The opinions expressed are her own.)

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