Biden warns Fla. seniors Romney tax plan will raise Social Security taxes

Biden took a more subdued, serious tone in the speech, making a careful argument in an attempt to chisel away at the "credibility" of the Republican ticket.

"Who are you going to believe?" he asked several times, charging that Romney cannot explain how he will pay for entitlement benefits in his budget because he refuses to raise taxes on the wealthy and the only other way to increase revenue is to raise taxes on the middle class.

Romney's campaign denies this claim. “Mitt Romney and Paul Ryan have a plan to save and strengthen Social Security that does not raise taxes and ensures that our middle-class seniors receive all of the benefits they've earned," Romney spokesman Ryan Williams said in a statement. "Vice President Biden is using Social Security to fabricate the Obama campaign’s latest false attacks. However, these attacks will backfire when voters learn he has repeatedly supported higher Social Security taxes, and that seniors face a 25 percent across-the-board benefit cut because of President Obama’s failure to lead on this issue."

Biden began by reminiscing about his own parents and grandparents as well as spending a few minutes discussing "strong women" in his life. He said a family value passed down from his grandfather explained his criticism of the Republican ticket: "Show me your budget; I'll tell you what you value."

"I'm not being critical, but they just have a different value set," he said of Romney and Paul Ryan. "Can you imagine me and Obama supporting any plan to raise Medicare out-of-pocket costs on seniors by $6,400?"

For more on Biden's remarks, click here.