When George Stephanopoulos asked Mitt Romney in a Sept. 14 "Good Morning America" interview what he's learned about President Obama as a debater, the former Massachusetts governor replied, "I think he's going to say a lot of things that aren't accurate."

If Mr. Obama's debate performance mirrors his campaign, Mr. Romney's prediction will be dead on. To get a sense of how comprehensive the president's assault on the truth has been, consider some of his false claims in recent speeches and ads.

One Obama spot says, "To pay for huge, new tax breaks for millionaires like him, Romney would have to raise taxes on the middle class: $2,000 for a family with children."

That claim has been thoroughly discredited, including by PolitiFact Virginia and editorials in this newspaper. Mr. Romney, unlike the president, is committed to cutting taxes for everyone, including the middle class.

Another ad says, "As a corporate raider, [Mr. Romney] shipped jobs to China and Mexico." In response, the Washington Post editorialized, "On just about every level, this ad is misleading, unfair and untrue." As recently as Sept. 17, Mr. Obama claimed in Ohio that Mr. Romney's "experience has been owning companies that were called 'pioneers' in the business of outsourcing jobs to countries like China." But that claim, too, is a fabrication.