In Indianapolis on Friday to boost Senate Democratic hopeful Joe Donnelly, Clinton said he hadn't expected to be so involved in the 2012 campaign. But Hillary Clinton is busy as America's chief diplomat and daughter Chelsea works for a broadcast network, he noted.
"So you're stuck with me," Clinton told the crowd.
Obama himself has cracked that he should appoint Clinton "secretary of explaining stuff."
The lighthearted tone and determined cooperation between Obama and Clinton is hard-won and may not end with the 2012 campaign.
The bruising 2008 Democratic primary between Obama and Hillary Clinton damaged relations between the families. Obama's appointment of Hillary Clinton as secretary of state, and her successes in the job, healed the relationship enough for Clinton to step in to help with Obama's re-election.
If Obama has Bill Clinton to thank for a second term, one way to pay back the debt could be Obama's support for a Hillary Clinton campaign of the future.
Among voters generally, Bill Clinton is more appealing than Obama. A CBS News/New York Times poll in September found 66 percent of registered voters with a favorable view of Clinton, compared with 45 percent for Obama.