DES MOINES — If U.S. Senate Majority Leader Mitch McConnell begins the confirmation of President Donald Trump’s nominee to full a Supreme Court vacancy before the November election — as he has said he will do — Sen. Chuck Grassley. R-Iowa, said Monday he will fulfill his “responsibility to evaluate the nominee on the merits, just as I always have.”Grassley, who as Judiciary Committee chairman in 2016, incurred the wrath of Democrats when he refused to hold hearings on the-President Barack Obama’s nomination of Judge Merrick Garland to the Supreme Court.He cited the so-called Biden Rule that stemmed from a speech then-Sen.