WASHINGTON – Eager to begin another assault on the credibility of those investigating him, President Donald Trump said Tuesday that he wants to know “what is taking so long” with an internal Justice Department investigation that is expected to cast a harsh spotlight on the FBI. The early-morning tweet underscores how the White House and Trump’s legal team view the upcoming watchdog report as a way to damage the reputation of fired FBI Director James Comey – and, by extension, discredit special counsel Robert Mueller’s investigation into possible ties between the Trump campaign and Russia. The report is expected to sharply criticize Comey’s handling of the Hillary Clinton email investigation, which the White House initially cited as the rationale for firing the FBI chief last year.