Nearly 12 years after he left office, Bill Clinton remains one of our most popular and compelling politicians. Many believe, probably correctly, that if the Constitution had allowed he could have won a third term as president in 2000, despite the sex scandals, his minor perjury rap and his impeachment by the House.

The Obama campaign plans to make full use of that popularity and his lingering association with good economic times, including four years of balanced budgets, at the Democratic convention in Charlotte, N.C.

According to the Associated Press, campaign and party officials were at pains to stress that President Barack Obama “personally” asked Clinton to place his name in nomination and that Clinton “enthusiastically” agreed.

Clinton is being given an exceptional piece of prime time to speak, the night before Obama makes his acceptance speech, a slot usually reserved for the running mate. Instead, Vice President Joe Biden will speak just ahead of Obama on Thursday night in Bank of America stadium.

Some commentators will unkindly recall Clinton’s debut on the national stage when as a rising star in the party the then-governor of Arkansas was invited to nominate Michael Dukakis at the 1988 convention in Atlanta. His speech was not only boring but seemingly interminable and when he finally said, “In conclusion,” the audience erupted in cheers.

Democratic strategists hope that Clinton’s presence will dramatize the party’s unity and draw a contrast with the Republicans, whose most recent president, George W. Bush, is not attending and whose nominee, Mitt Romney, is viewed skeptically by the party’s powerful right wing.

Clinton could be an effective campaigner for Obama this fall, although he can be famously undisciplined. This spring, when the Obama campaign was trying to paint Romney’s record at Bain Capital as one of plant closings and job outsourcing, Clinton praised Romney’s “sterling business career” and said he was more than qualified to run for president.

That perhaps is the downside of Clinton’s greatest political asset: He’s impossible to ignore, and the convention is not the last time this fall that Obama will have to call on the party’s most popular Democrat. Even if he can be something of a loose cannon, Clinton still musters a lot of political firepower.