According to Kantar Media, the most-aired political ad of the last decade came from the first Barack Obama presidential campaign, a spot that took aim at John McCain’s plan for health-care reform. The ball of yarn motif ended up depicting the trajectory of the McCain campaign in 2008, but the warnings Obama issued in this ad turned out to be prescient … about ObamaCare. Washington Post fact-checker Glenn Kessler parses this ad’s attacks, and notes that every single one of the criticisms Obama made about McCain’s reform turned out to be part of his own:

“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 Newsreported. “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.”

Kessler’s conclusion applies this lesson on a broader scale to campaign promises in general:

Even if your candidate wins, his warnings about the other side’s plans may turn out to be true.

Indeed, especially when dealing with candidates who promise fundamental transformation at the same time that they promise nothing will change (“If you like your plan, you can keep your plan”).