President Obama's campaign spent more than $1 billion on the 2012 election, but his top advisers have a message for future candidates: "You can’t buy the White House."

So says senior adviser David Axelrod, as he and other Obama aides reflected on the president's re-election victory in a conference call Thursday. Axelrod said that Republicans who believed that outside super PACs with nearly unlimited resources, such as Karl Rove’s American Crossroads, would be able to make the difference for GOP candidates were mistaken. Crossroads spent hundreds of millions on GOP races across the country, but according to one analysis saw a 6 percent return on that investment in victories.

“Literally billions were spent to try to unseat the president and change Congress and change the Senate,” Axelrod said. “If I were one of those billionaires funding Crossroads and other organizations, I’d be wanting to talk to someone and asking where my refund is because they didn’t get much for their money.”

Axelrod added that Republicans “have some soul-searching to do” after the results showed Obama winning a majority of moderate votes and far outpacing Mitt Romney among Hispanics and other minority groups.

Now that the president’s final campaign has come to a close, campaign manager Jim Messina said his vast organization will have a “conversation” with Obama’s supporters across the country about how to translate the energy and network in the field into future action.

But White House adviser David Plouffe said that it is not easy to simply hand over the Obama campaign organization to another Democratic candidate in 2016, because the enthusiasm for the president is organic.

“You just can’t transfer this,” Plouffe said. “People are not spending hours away from their families and job and contributing financially unless they believe in the candidate. … These people believed in Barack Obama.”

He added that “Candidates can try to build a grassroots network, but this does not happen because you have the best list or best technology. That’s not how this works. They have to build up that kind of emotional appeal.”