WASHINGTON — The White House on Friday formally blocked an attempt by former President Donald Trump to withhold documents from Congress related to the Jan. 6 attack on the Capitol, setting up a legal showdown between the current and former presidents over executive privilege. In a letter to the National Archives obtained by NBC News, White House Counsel Dana Remus rejected an attempt by Trump’s attorneys to withhold documents requested by the House Select Committee regarding the then-president’s activities on Jan. 6, writing that “President Biden has determined that an assertion of executive privilege is not in the best interests...