This was the year money would be reined in, chastened candidates would shrink from negativity and President Bush would be ubiquitous in his proud march across the deck of the aircraft carrier Abraham Lincoln — a moment political pundits dubbed “the photo opportunity of the century.’’

Of course, none of those predictions proved true. The two candidates for president, their boosters and detractors have spent more than $1.5 billion in the White House contest, a record sum.

The attack advertising began in March and never let up.

And it is Democrats, not Republicans, who have sought to exploit pictures of the president’s flight-suit promenade — as a symbol, in their view, of miscalculation rather than triumph in the war in Iraq.

Even Karl Rove, Bush’s chief political adviser, has expressed second thoughts about the “Mission Accomplished’’ banner famously strung overhead.

But that should be no surprise by now. This most unpredictable of campaigns — still stubbornly knotted in its last hours — has demolished any number of truths the political cognoscenti once held to be self-evident.

Among them:

— The candidate in each major party who raises the most money in the year leading up to an election invariably wins the nomination.

— Incumbent presidents win re-election — or lose — by substantial margins. Maybe.

— Negative campaigning turns people off and drives down voter participation.

— The Democratic nominee will be buried in an avalanche of Republican dollars. In fact, Sen. John F. Kerry has been awash in money, both the record-shattering sum he amassed and the many tens of millions raised by sympathetic groups.

— Big events — the nominating conventions, the debates — will turn the race decidedly in favor of one candidate or another. “This has been a dead heat on a merry-go-round,’’ Democratic pollster Peter S. Hart said.

Even the political map has thrown experts for a loop. Few would have guessed that Republicans would see last-minute opportunity in traditionally Democratic Hawaii, or that Democrats would make a serious play for GOP-leaning Nevada and Colorado.

How did the political intelligentsia get so much so wrong?

“We’ve just never before seen such depth of emotion, such strongly held views on both sides that can override conventional rules of thumb,’’ said Charles Cook, publisher of the nonpartisan Cook Political Report and one of the country’s leading election handicappers. “There is an exception to every rule, and this is an exceptional year.’’

Some things, however, do resist change. Take, for instance, negative advertising. Many surmised that a new law requiring candidates to take responsibility for ad content — “I’m George W. Bush, and I approve this message’’ — would shame candidates into running fewer attack spots.

But repeated academic studies have shown that voters have a high tolerance for negative advertising, as long as a candidate avoids what they see as “cheap shots.’’ “One of the things you have to do to get someone to vote for you is to tell them why they shouldn’t vote for the other candidate,’’ said Craig Brians, a political scientist at Virginia Tech and an expert on political advertising.