01/19/2012 07:41 pm ET

Callista Gingrich, Newt Gingrich's Wife, In The Spotlight At GOP Debate (PHOTOS)

WASHINGTON -- At Thursday night's Republican debate in South Carolina, only one person will likely receive as much attention as the candidates themselves: Callista Gingrich.

Newt Gingrich's third wife is back in the spotlight because of a new interview with his second wife, Marianne Gingrich, in which Marianne tells ABC that the former House speaker asked her for an "open marriage" in 1999 so that he could continue his long-term affair with Callista, a congressional staffer at the time.

Tonight, wherever the lights and cameras track Callista Gingrich, they'll also be tracking her hair -- a frozen, platinum blond bob that has sparked fascination among women eager to learn how she keeps it so perfect all the time.

But the Callista bob wasn't always the slick, smooth, helmet-y coif it is now. When she married Newt in 2000, Callista wore her hair longer and curlier, although still very blond.

Over the past 12 years, her haircut has morphed slowly into her signature disciplined bob, and her wardrobe has followed suit with more structure and fewer patterns.

As Callista Gingrich prepares to endure skeptical glances from some in the Republican audience tonight, that discipline might be just what she needs, along with a ready smile and another great hair day.

Ellie Krupnick contributed to this story.

CLICK on the slideshow to see Callista's style evolution.

Callista Gingrich