A major Times poll has found that voters’ doubts about President Biden deepened after his poor performance in the first debate, with Donald J. Trump taking by far his biggest lead of the campaign.Shane Goldmacher, a national political correspondent for The Times, explains what those results could mean for Mr. Biden’s future.Guest: Shane Goldmacher, a national political correspondent for The New York Times.Background reading: Mr. Trump now leads Mr. Biden 49 percent to 43 percent among likely voters nationally.Mr. Biden has been left fighting for his political future after his faltering debate performance. Read the latest.For more information on today’s episode, visit nytimes.com/thedaily. Transcripts of each episode will be made available by the next workday.