President Joe Biden and his top aides sought to calm growing anxiety among his allies on Capitol Hill and top Democrats as he vowed on Wednesday to continue his re-election campaign, rejecting pressure from within the party to withdraw. Mr. Biden's poor performance in the debate had prompted questions about him. "I'm running, I'm the leader of the Democratic Party, and nobody's pushing me out [of the race]," a senior aide reportedly posted Mr. Biden's comments on social media platform X. Mr. Biden and Mr. Harris made a surprise appearance on a conference call with the Democratic National Committee, according to three people familiar with the matter, which they described as a pep talk that emphasized the stakes in the election and returned to Mr. Biden's earlier post-debate comments that he would get back on his feet after being "knocked down."