Can We Believe the Presidential Polls?

Last week's CBS/New York Times poll had Obama ahead by nine points in Florida. That's not very likely.

I've seen a movie like this one before. I was in my 20s and director of the Texas Victory Committee for Reagan-Bush. Our headquarters was in an old mortuary in Austin. That seemed an appropriate venue when, on Oct. 8, 1980, the New York Times released its poll on the presidential race in Texas, one of 10 battlegrounds. (Yes, the Lone Star State was then a battleground.)

According to the Times, the contest was "a virtual dead heat," with President Jimmy Carter ahead despite earlier surveys showing Ronald Reagan winning. A large Hispanic turnout for Mr. Carter—and the fact that Texas was "far more Democratic than the nation" (only 16% of Texans identified themselves as Republicans then)—meant that Mr. Reagan "must do better among independents" to carry the state. Our hurriedly called strategy session at the mortuary had more than the normal complement of hand-wringers.

Then came more hard punches. On Oct. 13, Gallup put the race nationally at Carter 44%, Reagan 40%. The bottom appeared to fall out two weeks later when a new national Gallup poll had Carter 47%, Reagan 39%.

That produced more than a few empty chairs in phone banks across Texas. But most volunteers, grim and stoic, hung on, determined to stay until the bitter end. Only Election Day was not so bitter. Reagan carried all 10 of the Times' battleground states and defeated Mr. Carter by nearly 10 points.

Every election is different and this year won't replicate 1980. But context might be helpful to edgy supporters of Mitt Romney.

In the past 30 days, there were 91 national polls (including each Gallup and Rasmussen daily tracking survey). Mr. Obama was at or above the magic number of 50% in just 20. His average was 47.9%. Mr. Romney's was 45.5%.

There were 40 national polls over the same period in 2004. President George W. Bush was 50% or higher in 18. His average was 49%; Massachusetts Sen. John Kerry was at 43.8%. An Oct. 4, 2004, story in the New York Times declared the Bush/Kerry race "a dead heat" and asked "whether Mr. Bush can regain the advantage."

Mr. Bush was hitting the vital 50% mark in almost half the polls (unlike Mr. Obama) and had a lead over Mr. Kerry twice as large as the one Mr. Obama now holds over Mr. Romney. So why was the 2004 race "a dead heat" while many commentators today say Mr. Obama is the clear favorite?

The reality is that 2012 is a horse race and will remain so. An incumbent below 50% is in grave danger. On Election Day he'll usually receive less than his final poll number. That's because his detractors are more likely to turn out, and undecideds are more resistant to voting for him.

Then there is the tsunami of state-level polls. Last week, there were 46 polls in 22 states; the week before, 52 polls in 18 states; and the week before that, 41 polls in 20 states. They're endowed by the media with a scientific precision they simply don't have.

Take last week's CBS/New York Times Florida survey, which had Mr. Obama leading Mr. Romney by nine points. The poll sampled more Democrats than Republicans—nine percentage points more. Yet the Democratic advantage in the 2008 presidential exit polls was three percentage points. Does it seem probable that Florida Democrats will turn out in higher numbers in 2012, especially when their registration edge over Republicans dropped by 22% in the past four years?

On Aug. 2, radio talk-show host Hugh Hewitt asked Peter Brown, assistant director of the Quinnipiac University polling organization—which runs the CBS/NYT battleground state polls, including last week's Florida poll—if he expected a Democratic advantage in the Sunshine State three times what it was last time. Mr. Brown responded that "I think it is probably unlikely," but defended his polling organization's record.

Both candidates have advantages as the race enters its final month. Mr. Obama is slightly ahead (but short of 50%). Late-deciding independents will probably break more for Mr. Romney. Clear-eyed operatives in Boston and Chicago know this and are only playing head games with their opposition when they assert otherwise.

Team Obama's relentless efforts to denigrate Mr. Romney as a sure loser appear to have convinced the Republican candidate that he must run as the underdog. This will make the naturally cautious Mr. Romney more aggressive, energized and specific about his agenda in the campaign's closing weeks than he might have been. It will also make his victory more likely. America likes come-from-behind winners.

This article originally appeared on WSJ.com on Wednesday, October 3, 2012.