(CNN) -- President Barack Obama and GOP vice presidential nominee Paul Ryan on Friday traded sharp criticism over health care reforms and Medicare, with each telling a leading advocacy group for senior citizens that the other was being untruthful. "Contrary to what you've heard and what you may hear from subsequent speakers, Obamacare actually strengthened Medicare," the president told the AARP Liffe@50+ event, using the nickname for the 2010 Affordable Care Act that passed with no Republican support. In particular, he called the claim by Ryan and other Republicans that $716 billion is being cut from Medicare to fund the health care bill "simply not true."
@highlight
NEW: Sen. Reid says Romney still isn't coming clean on taxes
@highlight
Paul Ryan gets mixed reception at AARP event
@highlight
Ryan and President Obama accuse each other of being untruthful
@highlight
Obama says leadership means rejecting bad ideas
In his remarks, Obama argued that Medicare savings come from "using the purchasing power of @placeholder to say to doctors and hospitals and insurance companies: 'You guys need to work smarter."
He noted that @placeholder supported the 2010 health care reform act and opposed Ryan's Medicare proposal.