But why now? Because the debate is coming up and they don't want Biden to repeat the same lie he's been saying for 7 years...On CNN Biden said the reason he decided to run for president was because Trump called White Supremacists "Fine People" at Charlottesville and Anderson Cooper just nodded in bovine agreement. And the rest of the left wing media repeated the lie for years which is now rated false by Snopes.
Video of Trump's comment in context here-
And here is a long list of Biden lies compiled by PolitiFact. When you hit the bottom of the page click the "next" button to go to the next pages, there's too many lies to fit on one page.
VIDEO - The Long List of Joe Biden Lies - From 40 Years Ago Until Now