The president referred to a 60 Minutes interview during which Romney supposedly said taxing millionaires at a lower rate than bus drivers would boost the economy. Here’s how the president characterized his opponents comments:

“[Romney] was on 60 Minutes just two weeks ago and he was asked: Is it fair for somebody like you, making $20 million a year, to pay a lower tax rate than a nurse or a bus driver, somebody making $50,000 year? And he said,‘Yes, I think that's fair.’ Not only that, he said, ‘I think that's what grows the economy.’”

The president described the exchange accurately. Here’s a transcript of the relevant part of that conversation between Romney and 60 Minutes reporter Scott Pelley:

PELLEY: “You made on your investments, personally, about twenty million dollars last year and you paid fourteen percent in federal taxes. That`s the capital gains rate. Is that fair to the guy who makes fifty thousand dollars and paid a higher rate than you did?

ROMNEY: It is a low rate. And one of the reasons why the capital gains tax rate is lower is because capital has already been taxed once at the corporate level, as high as thirty-five percent.

PELLEY: So you think it is fair?

MITT ROMNEY: Yeah, I think it’s the right way to encourage economic growth, to get people to invest, to start businesses, to put people to work.

The president’s comments suggested that Romney thinks the economy will grow by virtue of bus drivers paying less than millionaires. But the Republican candidate was really saying that limiting taxes on investment income will encourage people to invest more of their money into the economy.

Note that none of this has anything to do with individual-income tax, for which both Romney and Obama have both proposed progressive systems requiring higher earners to pay more than lower earners.