It has been a long time at the top, 16 years in which they dominated Democratic national politics, first from his perch at the White House with her as first lady, then her seven years as a senator from New York and Democratic presidential candidate.
They are receding from the limelight to give way to Mr Obama's historic run for president, but they are not going quietly.
Speaking at the Democratic National Convention on Tuesday night, Mrs Clinton urged her millions of supporters to back Mr Obama, and Bill has a prime-time address on Wednesday night.
'Whether you voted for me, or voted for Barack, the time is now to unite as a single party with a single purpose,' she said. 'We are on the same team, and none of us can afford to sit on the sidelines.'
All eyes were on the couple this week to see how far they go in their praise of Mr Obama in the name of unity, to repair the rift that erupted between the Obama and Clinton camps after their tough Democratic primary battle and his decision not to select her as his vice presidential running mate.
While Mrs Hillary Clinton was unequivocal in her support for Mr Obama, Clinton advisers are putting out word that it is Mr Bill Clinton who is having the most trouble warming up to Mr Obama.
A two-term president himself, Mr Bill Clinton was accused of injecting racial politics into the campaign by Mr Obama, who would be America's first black president, and Mr Clinton was livid about the charge.
'There is still work to do on the Bill Clinton front. He feels like the Obama campaign ran against and systematically dismissed his administration's accomplishments. And he feels like he was painted as a racist during the primary process,' Mr Howard Wolfson, former Mrs Hillary Clinton senior campaign strategist, wrote in The New Republic this week.
Mrs Clinton has shown a greater ability to put the past behind her, quickly attacking a television advertisement by Republican opponent John McCain that sought to use her words against Obama.
Party unity
Some Democrats say she is all in favour of party unity, and in any event does not want to be blamed if Mr Obama does not win the Nov 4 election against Mr McCain.
'I think everybody's best interests are in patching it up,' said Democratic strategist Bud Jackson.
Some Clinton believers think that should Mr Obama stumble in November, then maybe she could again rise as the go-to Democrat to run in 2012, when she would be 64.
'You can just never count these two out,' said a former Clinton White House official, who spoke on condition of anonymity.
Nonetheless, this Democrat said, their back-to-back appearances this week has the feel of 'sort of a capstone' on the Clinton era, a passing of the torch to Obama.
But many Clinton supporters are reluctant to let go and represent a possible threat to Mr Obama should they vote for Mr McCain in battleground states likely to make the difference as to who wins the election.
One of those fence-straddlers is Ms Lynn Forester, a Clinton fundraiser.
She told the Fox News Channel's 'Neil Cavuto' on Tuesday that Mr Obama still has work to do to win over her and other people like her.
'Everybody who believes, 'I'll vote Democrat no matter who it is,' this is easy for them. People who say, 'I want the best candidate, I want the person who has the best character,' they're having some question about this, and that's legitimate,' Ms Forester said. -- REUTERS