NEW YORK– In one week, Michelle Obama sat for a formal White House portrait, dressed in somber, tailored clothes; posed for a snazzy People magazine cover, dressed in a slightly down-market, hot-pink lace outfit that showed plenty of skin; let the national media know that the First Family would be getting its new puppy from a rescue shelter; and had her press office mention casually that “secretaries and policy makers” had been invited for popcorn and movies at the White House.