Washington — President Joe Biden is fighting to save his endangered reelection effort Friday as he holds a rally and sits down for a network television interview in a pivotal battleground state, with his every answer sure to be scrutinized for evidence of his competency and fitness to run for office. [time-brightcove not-tgx=”true”] It could be a watershed moment for Biden, who is under pressure to bow out of the campaign after his disastrous debate performance against Republican Donald Trump ignited concern that the 81-year-old Democrat is not up for the job for another four years. The interview with ABC’s George Stephanopoulos, being taped after a campaign rally in Madison, Wisconsin, is expected to be intensive and probing, and two people familiar with the president’s efforts said he had been preparing aggressively.