Margaret "Midge" Costanza (November 28, 1932 – March 23, 2010) was an American presidential advisor and a social and political activist.

In 1976 when Georgia Governor Jimmy Carter ran for President of the United States, Costanza served as co-chair of his New York campaign operation and gave a seconding speech for him at the Democratic National Convention (Carter had been a volunteer in Costanza's congressional campaign two years prior).

Public disagreements with some of the president's policies caused controversy and saw Costanza's role in the White House diminished.

[8] [9] Costanza had been popular with women's groups, and had earned herself a Newsweek cover titled "Woman in the White House".

[11] Costanza became executive director of her friend Shirley MacLaine's "Higher Self" seminars after moving to Los Angeles and later became vice-president at Alan Landsburg Productions, where she made commercial films and advertisements.

She served on many service group boards of directors, including the AIDS research organization Search Alliance and the National Gay Rights Advocates.

[1] Moving to San Diego County, California, in 1990, Costanza coached candidates for office in public speaking, serving as the coordinator for Barbara Boxer's winning United States Senate in the Year of the Woman, 1992, and as manager for Kathleen Brown's failed gubernatorial candidacy in 1994.