Instead of blaming the Secret Service for the party crashers who infiltrated last week’s state dinner, fingers are starting to point at the Obama administration itself. White House Social Secretary Desiree Rogers admitted to the Associated Press that no one from her office was manning the door. New Yorkers are used to seeing platoons of efficient p.r. staffers at entrances to private parties, armed with clipboards, checking names against guest lists. But Sen. Chuck Schumer implied it was amateur hour at the White House. “It doesn’t seem too hard to have a checklist at the door and to make sure that the only people who get in are on the checklist,” Schumer said. Instead of preparing for the historic event, Rogers was spotted at Pastis on Ninth Avenue just three days before.