An extensive accounting of more than 50,000 commercials by Kantar Media’s Campaign Media Analysis Group, which tracks political advertising, has determined that the single most-aired campaign ad of the past 10 years was a 30-second spot for Sen. Barack Obama attacking Sen. John McCain (R-Ariz.) on his health-care plan.

The ad featured a simple ball of yarn.

“We knew uncovering the details of McCain’s health care plan was a political imperative, but we needed to do it in a way that broke through the advertising clutter,” says AKPD Message and Media, which produced the ad. “We wanted an image that was unique and powerful enough to stick in voters’ heads, even if they were watching TV with the sound turned down.”

Douglas Holtz-Eakin, senior policy adviser to McCain, remembers the ad well. “I have PTSD from that ad,” he said. “I thought I saw it a thousand times a day. It left me just numb. I still see that yarn in my sleep.”

In 2008, our colleagues at were not that impressed with the commercial’s claims, reviewing it as part of an article titled “Health Care Spin.” They noted that the ad highlighted the fact that McCain proposed a tax on health benefits but never mentioned that he also proposed a tax credit that, for many Americans, would offset any tax increase.

Of course, McCain did not become president. And Obama, who has argued against adopting an individual mandate, as proposed by Hillary Clinton, ended up embracing exactly that option—and even accepted a variation of an idea from McCain that he criticizes in this ad.

Politicians change their minds—and their policies—all the time, sometimes for political reasons but also because circumstances change. But within the benefit of hindsight, could McCain have made the same attack ad against Obama? The Truth Teller Video above also examines the claims.

“McCain would tax health benefits for the first time ever”

Starting in 2018, the Affordable Care Act will impose a 40-percent excise tax, known as the “Cadillac tax,” on generous health plans, which is defined as a plan that exceeds an annual limit of $10,200 for an individual and $27,500 for a family. Proponents of the provision believe it will help hold down health-care costs.

McCain wanted to do away with the tax-free status of employer-provided health benefits entirely. (Employer-provided benefits is a bit of an accident of history: Companies began to extend health benefits in respond to government-imposed wage freezes in the 1950s.) So health benefits would have been taxed as ordinary income, but people would also have received a tax credit.

It’s not quite the same but certainly Obama is taxing health benefits for the first time.

“His plan would raise costs for employers offering health care, so your coverage would be reduced or dropped completely.”

Though the Cadillac tax is not in effect yet, surveys show that companies are already redesigning their plans to avoid the looming tax.

“A survey by the International Foundation of Employees Benefits Plans (IFEBP) found that 16.8 percent of respondents had already started to redesign their health plans to avoid the “Cadillac” tax and 40 percent said they are considering action,” NBC News reported. “A survey of Fortune 1000 companies by Towers Watson, a top benefits consulting firm, found a much higher number. Sixty percent of the these major companies, which employ about 20 million American workers, say the looming excise tax is already having a ‘moderate’ or ‘significant’ influence on benefits decisions for 2014 and 2015.”

“McCain won’t require coverage for preexisting conditions”

This was a point of real contention, as Obama said he would mandate coverage and McCain wanted to expand high-risk pools in many states that were designed to cover those who had been denied coverage or had high health-care costs. McCain’s proposal was a more free-market approach, given that relatively few people have extremely expensive medical problems. He figured it would be better to create special insurance pools, modeled on existing states pools, rather than force insurance companies to include them with everyone else. (The Post reported at the time the experience in the state pools was quite mixed.)

Obama did mandate coverage of pre-existing conditions as he promised, but he also adopted the concept of high-risk pools as a $5 billion transitional program between the adoption of the law in 2010 and the implementation of the Affordable Care Act in 2014.

The Bottom Line

This ad is a textbook example of why no voter should cast ballots based on promises or claims made in campaign ads. Such ads serve more as a guide for the general direction a candidate might take, such as McCain wanting a more free-market approach and Obama advocating a more top-down government-managed system.

But if you are counting on the specifics to turn out to be true, don’t hold your breath. Even if your candidate wins, his warnings about the other side’s plans may turn out to be true.

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The most-aired political ad of the past 10 years comes from 2008, when then-Sen. Barack Obama attacked Sen. John McCain's health care plan. But as president, Obama adopted some of the same ideas he attacked then. Truth Teller meets Throwback Thursday. (Julie Percha/The Washington Post)