But Bill Clinton possesses better political judgment than any of his Democratic peers, and it was on full display in his convention speech. Instead of suiting up in the culture war, Clinton pitched his message to employment-focused independents. He sympathized with public anger and frustration, but claimed that Obama has “laid the foundations for… shared prosperity.” Clinton identified Democratic ideology with “free enterprise” and “individual initiative” and “advancing economic opportunity and economic empowerment.” He praised past Republican presidents for their achievements and assured Americans that democracy doesn’t “need to be a blood sport.” Clinton explained Obama’s own policies better than the president has ever done. He defended Obama from Republican attacks with humor and skill. And Clinton imputed to Obama a belief in “constructive cooperation” which the president has rarely shown. In fact, many of Clinton’s items of praise for Obama seemed more like praise for Clinton’s earlier self.

Clinton’s political brilliance is always something of a mixed blessing for Democrats. It provides a contrast to the current occupant of the White House. This is not only a matter of skill but of strategy. Clinton – who was elected chair of the Democratic Leadership Council in 1990 – spent years cultivating a more moderate image for his party. As president, he was willing to work with unreconstructed liberals such as Ted Kennedy and Richard Gephardt, but also willing (on occasion) to distance himself from them. Clinton’s signature achievements – a balanced budget, NAFTA, welfare reform, the expansion of EITC – were a mixed ideological lot.

From the earliest days of his administration, Obama lacked ideological creativity. He almost immediately polarized the country with a deeply partisan health care proposal – passed on a party line vote, then repudiated in the 2010 midterm election. Obama’s Keynesianism is typical, tired, ineffective and expensive. More recently, he has attempted to shore up his base by embracing liberal cultural issues – an appeal accurately reflected on Tuesday night.

There is nothing Clintonian about Obama’s governing approach, which more closely resembles Walter Mondale or Michael Dukakis if they had ridden to office on the wave of a financial crisis. Obama is an utterly conventional ideological figure. Clinton was anything but.

Clinton’s appearance tonight was a reminder of his political gifts, and of the limits of his political influence. The New Democrat revolution was embodied in one, exceptional individual. But he left his party unchanged. In his absence, Democrats reverted to ideological type. And Clinton is now left defending a president who has ignored his lessons.