Sales for Michelle Obama memoir top 2 million copies

Michelle Obama's Becomingis selling at a pace rarely seen for a political memoir, or any nonfiction book.

Combined hardcover, e-book and audio sales in the U.S. and Canada topped 2 million copies in the first 15 days, Crown Publishing announced Friday.

By comparison, former secretary of state Hillary Rodham Clinton's memoir Living Historyneeded a month to sell 1 million copies.

Former U.S. president George W. Bush's Decision Pointstook several weeks to reach 2 million.

Former president Bill Clinton's My Lifequickly sold 1 million copies but took far longer to hit 2 million.

Becoming,which came out Nov. 13, now has 3.4 million hardcover copies in print.

The former first lady is in the midst of a promotional tour, with guests including Oprah Winfrey and Reese Witherspoon.