Michael Bloomberg, the billionaire former mayor of New York City, has told his aides to draw up plans for an independent campaign for the U.S. presidency, according to a source familiar with the situation. Bloomberg has advised friends and associates that he would be willing to spend at least $1 billion of his own money on a campaign for the November 2016 election, according to the source, who spoke on condition on anonymity to discuss the former mayor's thinking. News of Bloomberg mulling a presidential run was first reported Saturday by the New York Times.