Sen. Kirsten Gillibrand of New York is one of the most talked-about potential Democratic candidates for the White House in 2020. But she has also turned into a thorn in the side of the Department of Justice as she holds up one of DOJ's highest-profile postings. The junior senator from New York plans to use her “blue-slip prerogative” to block the confirmation of Geoffrey S. Berman, if he is nominated by President Trump to be the United States attorney for the Southern District of New York, Gillibrand spokesman Glen Caplin told Fox News. Berman, 58, a former prosecutor in the...