We don't yet know how many people watched Bill Clinton's speech last night, but since on the first night of the Democratic convention ratings were a bit higher than for the Republican convention, it's fair to assume we're talking about something in the vicinity of 30 million viewers. Which is fine, but it isn't anything close to a majority of the electorate. But even if most voters didn't actually see Clinton's speech, just the fact that everyone is aware that he's out there vouching for Barack Obama can have an impact. Because the basic question of the campaign-should we keep this guy and his people in charge, or turn it over to that other guy and his people?-will be answered in a context created by people's memories of recent history.

Republicans may not like to be reminded, but after all the energy they spent trying to take down Bill Clinton, he left office with spectacular approval ratings. In the final Gallup poll of his presidency, he was at 66 percent approval, which was around where he had been for most of the final three years of his presidency. For comparison, Ronald Reagan, whom many people mistakenly believe was a uniquely popular president, spent his last couple of years with approval ratings around 50 percent (though he got a spike to 63 percent in Gallup's last poll before he left office). And perhaps most importantly, George W. Bush spent his entire second term in negative approval territory, and when he left office his approval was in the twenties.

The reason that's important is that there are really only two former presidents people remember these days in anything that approaches a substantive, detailed way. One of them is remembered as a smashing success, and one of them is remembered as an epic failure. So saying to voters, "Do you want things to be like they were when Bill Clinton was president, or like they were when George W. Bush was president?" may not decide the election, but it's a powerful argument. It's no wonder Dubya's name was barely mentioned at the Republican convention.

Which brings me to this SNL sketch from when Clinton was leaving office. With a drink in his hand, he says, "Maybe it's the booze talking, but I'm pretty sure I took more crap from more people than any President in history, and yet I remain the most popular since Roosevelt. So y'all just suck on it."