 ABC's Stephen Portnoy. Democrats voicing concern after President Biden's performance at last night's debate against former President Trump, at times appearing to lose his train of thought. The Biden campaign attributed his stumbles and raspy voice to a cold. Here's ABC's Mary Bruce. This goes beyond just a rocky performance. As we've been saying, the president had to convince voters and Democrats that he can do this and he can win. And instead, he may have done the opposite, validating voters' trepidation about