First lady Michelle Obama with her daughters Malia, center, and Sasha.
President Barack Obama, first lady Michelle Obama and their daughters Sasha and Malia arrive on the South Lawn of the White House, Tuesday, Jan. 3, 2012, in Washington. The first family was returning from their family vacation to Hawaii. (AP Photo/Haraz N. Ghanbari)
President Barack Obama speaks in the East Room of the White House in Washington, Monday, Jan. 24, 2011, on a presidential initiative to support military families. (AP Photo/J. Scott Applewhite)
President Barack Obama, with his daughters Malia Obama and Sasha Obama, leave the Bunch of Grapes book store in Vineyard Haven, Mass., Friday, Aug. 20, 2010, where the First family is vacationing on Martha's Vineyard. (AP Photo/Carolyn Kaster)
Malia Obama, 11, left, and Sasha Obama, 8, center, with a family friend, look out from Gay Head Lighthouse while on vacation on Martha's Vineyard in Aquinnah, Mass. Thursday.
President Barack Obama and first lady Michelle Obama welcome military families to an Independence Day celebration on the South Lawn of the White House in Washington, Monday, July 4, 2011. (AP Photo/Charles Dharapak)
President Barack Obama holds hands with his daughters Malia, left, and Sasha, right, as they leave Sea Life Park, a marine wildlife park, with family friends, Tuesday, Dec. 27, 2011, in Waimanalo, Hawaii. (AP Photo/Carolyn Kaster)
President Barack Obama, with first lady Michelle Obama and daughters Malia, 12, left, and Sasha, 9, right, return to the White House in Washington, Tuesday, Jan. 4, 2011, and colder temperatures, after a family vacation in Hawaii. (AP Photo/J. Scott Applewhite)
WASHINGTON (AP) — Michelle Obama says her daughters are learning that even the kids of politicians have to have a thick skin. “Politics is tough,” the first lady said Tuesday. “That’s just sort of the nature of the beast.” But she said daughters Sasha and …