DES MOINES, Iowa -- More than any other candidate -- in either party -- Joe Biden has become Cassandra, vainly reminding voters of the foreign-policy stakes in this presidential race. Speaking to 200 voters at an Italian cultural center here Wednesday night (an impressive crowd for the night after Christmas in a normal political year), Biden declared, "This is one election in your life where you don't have to wonder what crisis the next president will face." Moving beyond Iraq, Biden, the chairman of the Senate Foreign Relations Committee, began confidently ticking them off: "Pakistan teetering. Russia moving in an authoritarian direction. Iran malleable but dangerous."

Listening to Biden, who was elected to the Senate from Delaware 35 years ago, I could not avoid recalling all the confident predictions tossed around in the wake of Sept. 11. Never again would an untested former governor (Mike Huckabee and Mitt Romney fit the description) be considered a serious presidential candidate. Never again would voters belittle decades of Washington experience. Never again would presidential campaigns spend more time debating gay marriage or ethanol subsidies than brooding about hair-trigger nuclear powers like Pakistan. Never again would American politics revolve more around personality than substance.

Against this backdrop, Biden's frustrations simmer just beneath the surface. "We have this debate going on about experience and change," he said. "And the two candidates with the most money talk about experience and change. I have more experience than all of them, including the candidate who says that she has the most experience. And I've changed more things than the guy who's talking about change."

Yes, Biden can be a little boastful and a tad loquacious (though he has pulled off amazing feats of brevity in the debates). But he also is a serious student of foreign policy who stresses that on Inauguration Day 2009, sometime between the afternoon parade and the evening balls, the man or woman who is elected next year, "will be in the Situation Room having to react as president." Implicit in Biden's prophesy is the inescapable reality that the decisions that this new president makes -- even before the rugs are changed in the Oval Office -- will have ripple effects throughout the world.

This week in Des Moines, where the skywalks are clogged with reporters and campaign staffers, it is easy to get the sense that the 2008 presidential campaign is just one joyous Winter Carnival of Politics. But Biden, who is normally an upbeat rather than dour campaigner, has taken on the role of truth-teller -- reminding voters that, in effect, as Iowa goes, so goes our future foreign policy toward Pakistan and Russia.