David Plouffe, a former senior adviser to President Obama, said in a tweet Thursday that Obama's 2012 reelection campaign never considered replacing Vice President Biden with Hillary Clinton, as a new book alleges.

The book, "Double Down," by Mark Halperin and John Heilemann, said Obama's campaign brass considered the switch and conducted focus groups on it in 2011.

But Plouffe said Obama advisers never entertained the idea.

Former President George W. Bush said in his memoir that he considered replacing then-vice president Dick Cheney during his 2004 reelection campaign.

Update 9:29 a.m. Friday:

Former White House chief of staff Bill Daley confirmed Friday that "it was looked at" but said the change never was seriously considered.

"...not for a moment was there a serious discussion or a belief that Joe Biden should be replaced, period," Daley told CBS "This Morning." "That doesn’t mean issues were not looked it. Lots of issues in 2011 were looked at.

"And it was looked at. But it was never seriously looked at in the sense that there was a belief that it ought to be done or needed to be done, and the truth is that any research that was done confirmed the fact that was not an issue voters cared about or thought should be done."

White House press secretary Jay Carney echoed Daley, saying it was merely a result of the fact that campaigns test out lots of things.

"Campaigns test everything. They run everything through the polls and focus groups. Whatever proposition it is, they test it out,” Carney stated told CNN. "Again, campaigns test everything, but as the book itself says, this was never considered by the President.”

Originally posted at 10:50 p.m. Tuesday.