Obama needs Clinton

Presidential elections are approaching in US and Obama is getting prepared. He embraced the ex president of USA Clinton. But the question is that why Obama needs Clinton now?
While Clinton overwhelmingly supporting Obama for re-election

"I want to nominate a man cool on the outside but burning for America on the inside.... I want Barack Obama to be the next president of the United States and I proudly nominate him as the standard bearer of the Democratic Party,"  Bill Clinton Democratic National Convention in Charlotte, N.C.

While Obama declared Bill Clinton as his secretary of explaining stuff ah poor Hillary maybe wasn't able to explain "stuff" to Obama.

 Clinton supported Obama's financial plan completely in his  speech during the national convention

But the question is does Obama also need a explaining secretary in form of Bush?

And is Obama going to repeat all those mistakes which were done by Bush and Clinton.

American people have to decide weather the want a change now or not?

Or they still see a HOPE in the Obama's leadership which previously failed to fulfil the dreams that he gave to his nation.