Does the 2012 campaign look a lot like the 2004 campaign? Many Democrats think so.
And there are some resemblances. As in 2004, current polling suggests a close race and shows only about a dozen states in contention.
As in 2004, the incumbent has been running negative ads against the challenger, hoping to disqualify him as Bill Clinton disqualified Bob Dole in 1996. Many Democrats think that Barack Obama's attacks on Mitt Romney's business career will have the same effect that they think the Swift Boat Veterans for Truth ads had on John Kerry in 2004.
But, as William Galston of the Brookings Institution, an alumnus of the Clinton White House, writes in The New Republic, "the evidence in favor of all these propositions is remarkably thin."
Galston points out that in 2004 no single issue was as prominent as the economy is this year and that on most significant issues George W. Bush had a clear edge by the end of the campaign. He cites polling evidence that the Swift Boat ads hurt Kerry less than did Bush ads replaying his March statement that "I did actually vote for the $87 billion before I voted against it."
Also, he points out that many more voters this year think the nation is seriously off on the wrong track and that the economy is in trouble. Obama's job rating now is weaker than Bush's was then.
Galston, as usual, is on target. His analysis tracks with the statement of Democratic pollster Peter Hart (for whom I worked from 1974 to 1981) that Obama's chances are "no better than 50 percent."
But there are at least two other salient differences between 2004 and 2012.
One is that the 2004 election occurred during a period of unusual stability in American voting behavior.
In the preceding four congressional elections, Republicans won between 48 and 51 percent of the popular vote for the House and Democrats won between 46 and 49 percent. In 2004 the parties' percentages in both the presidential and congressional popular vote were within the same narrow ranges.
Since then, voting behavior has been much more volatile. In the last three congressional elections, Republicans' share of the House popular vote has ranged from 43 to 52 percent and Democrats' share from 45 to 54 percent.
In 2004, only three states cast their electoral votes for a different party than in 2000, and the margins were narrow in all cases.
In other words, almost all voters in 2004 were firmly committed to one party or the other. Bush political supremo Karl Rove was right in saying there were few uncommitted voters and that his campaign's big task was to turn out the faithful. The Kerry campaign operated on the same assumption.
But in recent years, lots of American voters, at least by historical standards, have flipped from one party to the other, and in both directions.
The conventional wisdom is that we know with certainty the identity of the dozen or so battleground states. But the list has changed since 2008.
In 2008, Obama carried Indiana and lost Missouri by only 3,903 votes. Today, Indiana and Missouri aren't on anyone's target list.
In contrast, most analysts' battleground list this year includes Michigan and Wisconsin, which Obama carried in 2008 with 57 and 56 percent of the vote.
There's another difference between 2004 and 2012 that is salient. In 2004, George W. Bush's Republican base was pretty much united on issues. Foreign policy realists and neocons were all on board.
Cultural conservatives supported the Bush tax cuts. Few economic conservatives had much problem with Bush's stands on abortion or embryonic stem cell research.
Barack Obama's Democratic base is more heterogeneous. He probably increased turnout among young voters by endorsing same-sex marriage. But he risked turning off the many black voters who are solidly opposed.
Blocking the Keystone XL oil pipeline from Canada pleased gentry liberals who embrace every green cause. But private-sector labor unions don't like it a bit.
Bashing Romney's record at Bain and Co. may be helping him with some modest-income voters. But it risks antagonizing the affluent, which is a problem for a candidate who last time ran even, 49 to 49 percent, among those with incomes over $100,000.
Every campaign cycle is different, and 2012 is more different from 2004 than many Democrats think.