DES MOINES — Since the proposed legislation got a shot in the arm from President Donald Trump, Sen. Chuck Grassley, R-Iowa, is more optimistic about passage this year of his bipartisan plan to lower prescription drug prices.To get it to the floor of the Republican-controlled U.S. Senate, however, he’ll have to persuade Senate Majority Leader Mitch McConnell.“It’s my job to make the leader of the Senate comfortable in bringing it up,” Grassley said Tuesday about his Prescription Drug Pricing Reduction Act.