WASHINGTON (Reuters) - Robert Mueller brought an enviable reputation as the architect of the modern FBI and a force behind major criminal prosecutions to his job as special counsel investigating Russia’s role in the 2016 U.S. election but has encountered a relentless campaign by President Donald Trump to discredit the probe. Mueller, a longtime Republican, received bipartisan praise when he was named as special counsel in May 2017 to take over the Russia investigation after Trump fired FBI Director James Comey, whose agency had led the probe. Trump and allies in the Republican Party and conservative media have sought to...