See The Hill, "Warren admits she's 'concerned' about her campaign in wake of heritage controversy."
But it gets worse.
Warren may have issued yet another whopper yesterday, about how her parents "eloped." See Michael Patrick Leahy, "Exclusive: Eloped? Elizabeth Warren's Parents' Married in Religious Ceremony." It's not clear if Warren's parents married in church or in a private religious ceremony. Ed Morrissey has a big post up on this: "Warren: My parents had to elope because my mother was 1/16th Cherokee, or something..." (Via Memeorandum.)
And see William Jacobson, "Oh Elizabeth, there you go again."