New York ? Corporations are people. The fundamentals of the economy are strong. I voted for the $87 billion before I voted against it.

From Mitt Romney this month to John McCain in 2008 and John Kerry four years earlier, presidential candidates are caught telling the truth by accident in every campaign, blurting a phrase that is both factual but politically ill-advised.

Those moments speak to the deeply contradictory nature of American politics.

Voters say they want authentic, straight-talking candidates. But voters also tend to punish candidates who veer too far off script or who make assertions that, while true, cause people to cringe and question whether these politicians are out of touch with those they seek to represent.

Consider Romney, the early GOP front-runner who recently confronted a heckler in Iowa who was demanding higher taxes on corporations.

“Corporations are people, my friend,” the former Massachusetts governor shot back. “Everything corporations earn ultimately goes to people.”

Romney said it again at a campaign event in New Hampshire on Wednesday.

“When you say tax corporations, steel, vinyl, concrete, they don’t pay taxes. Only people do,” he said.

Corporations are made up of the people who work for them and stockholders who benefit from their profits. The Supreme Court said as much last year when it eased restrictions on campaign spending by corporations, saying businesses deserve the same freedom of speech individuals enjoy.

But was it smart for Romney to say, given the nation’s high unemployment and deep resentment of Wall Street? Probably not.

Democrats, predictably, pounced. President Barack Obama said he disagreed with the notion that corporate tax breaks are “good for ordinary Americans.”

It’s possible that Romney’s comment won’t damage his campaign because Republican primary voters tend to view business interests more favorably than do Democrats. But because of his wealth and history at Bain Capital, a private equity firm that created jobs in some places but made them disappear elsewhere through consolidation, the remark could reinforce the perception that Romney is disconnected from the concerns of working people.

“The gaffes that get traction tend to be the ones that fit a narrative that already exists about the candidate,” said Marc Hetherington, a political science professor at Vanderbilt University who studies campaign rhetoric. “Since corporations are very unpopular right now, it could really stick to someone like Romney who is so identified with the business community.”

Massachusetts Sen. Kerry, the 2004 Democratic nominee, learned a hard lesson about reinforcing an existing story line. He opposed money for the war in Iraq and voted against the legislation when it came up for final consideration. But he had gone along with an earlier version.

At one point, he told supporters: “I actually did vote for the $87 billion before I voted against it.” He was trying to explain that he wanted to ensure troops had the necessary equipment, but at the same time hoped to convey a message of opposition to the war.

The result was the Republicans cast Kerry as a flip-flopper in contrast with President George W. Bush’s image of strength and resolve. Bush narrowly won re-election that year.

In the fall of 2007, Hillary Rodham Clinton found herself in an uncomfortable spot just as Obama was gaining traction in the Democratic primary in part by railing against special interests.

Before a liberal audience and with Obama on stage nearby, Clinton launched a spirited defense of lobbyists — inadvertently burnishing her reputation as a protector of the status quo in Washington.

“A lot of these lobbyists, whether you like it or not, represent real Americans,” she said. “They represent nurses, they represent social workers, they represent corporations that employ a lot of people.”

It was true, but ill-timed and problematic, particularly in front of a progressive audience that already doubted Clinton’s commitment to liberal issues.