In many respects it seems to me that Obama is running more against himself and his first term than he is against Romney. I think Clinton addressing the Democratic National Convention (while Hillary stayed as far away as possible) is another manifestation of that.
Obama has not governed at all like Clinton. After his first two years as President and after the Democrats lost control of both the House and the Senate, Clinton moved to the middle. After his first two years as President and after the Democrats lost control of the House, Obama has moved even more aggressively to the far left. That and the obvious economic results of that do not earn Obama another four years so he is hoping that voters roll back the clock twenty years.
"Always looking 'forward,' President Obama has asked Bill Clinton—who was elected to the presidency 20 years ago—to...suggest to the American people (whether explicitly or implicitly) that this is really a choice between Clinton and George W. Bush, rather than between Obama and Mitt Romney. If you're Obama, this beats running on your record.
The only problem with this—in addition to the fact that Romney isn't Bush (and Paul Ryan isn't Dick Cheney)—is that Obama's record doesn't bear much resemblance to Clinton's. One could point to the rather obvious differences between the strong Clinton economy and the anemic Obama economy, between Clinton's signing welfare reform into law and Obama's undermining it via executive order, between Clinton's tacking to the center to work with Republicans and Obama's not moving to the center but playing to his base (rejecting the Keystone Pipeline, embracing gay marriage, making it illegal for Americans to offer or to choose health plans that don't include 'free' birth control, 'free' sterilization, and 'free' access to the abortion drug ella).
But one thing perhaps highlights the difference between Clinton and Obama most clearly: The increase in the national debt on their respective watches. Both men enjoyed two years of single-party control in Washington before they subsequently lost one (Obama) or both (Clinton) houses of Congress. In this way, their circumstances have been similar, but their results have not."
The $4.351 Trillion Difference Between Obama & Clinton | The Weekly Standard