Some members of President Joe Biden's cabinet have privately discussed whether it is time for his closest advisers to join him in considering the increasingly bleak prospects, according to a person familiar with the discussions. Instead of trying to cast Mr. Biden aside, top officials themselves have discussed whether he has reached a tipping point in his re-election campaign this year, the sources said. In conversations, the cabinet members acknowledged that voters had doubts about the president's health and ability to defeat Mr. Trump again. But cabinet officials, like many prominent Democrats, ultimately concluded that it was up to the president and a small group of close, longtime aides to discuss the issue in detail. But another person familiar with the discussions stressed that there was no indication that Mr. Biden was incapable of serving out the remainder of his term, or that the cabinet might move to remove him.