Ann Romney to Fill in for Robin Roberts on ‘Good Morning America’ (Exclusive)

Ann Romney, wife of Republican presidential candidate Mitt Romney, will fill in for Good Morning America anchor Robin Roberts on Oct. 10.

The booking, which has been in the works since last summer, comes on the heels of Mitt Romney‘s dominant performance Wednesday in the first presidential debate. Romney will guest-host the morning program alongside Roberts’ co-anchor George Stephanopoulos and correspondents Lara Spencer, Josh Elliott and Sam Champion.

She joins previously announced pinch-hitters Stephen Colbert, Oprah Winfrey, the cast of Modern Family and Roberts’ ABC News colleagues Diane Sawyer, Katie Couric and Barbara Walters. Jessica Simpson guest-hosted GMA on Sept. 11.

ABC News also has been in discussions with first lady Michelle Obama to guest-host the program, and sources at the news division say it is simply a matter of finding an opening on her schedule. Given President Obama’s performance at the debate, the Obama campaign could certainly use some of his wife’s considerable personal capital right about now.

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As it is, the morning show audience will give Ann Romney another mass media opportunity to get her husband’s message out to potential voters. A similar security protocol will be in place as when the first lady visited GMA in May. So Romney is not expected to appear outside of GMA‘s Times Square Studio, where anchors traditionally mingle with the sign-waving crowds in what is one of the busiest thoroughfares in the country.

Romney, who has battled multiple sclerosis and underwent a lumpectomy in 2008, reached out to Roberts on Twitter following Roberts’ on-air goodbye from GMA for medical leave. “Keep on fighting,” the wife of the Republican presidential nominee wrote. “We all stand with you!”

Roberts had a bone marrow transplant Sept. 20, with her sister Sally-Ann Roberts as her donor. Her progress has been closely tracked on GMA and via the show’s website. Roberts beat breast cancer five years ago. But earlier this year, she learned that she had myelodysplastic syndrome (MDS), a rare blood disease that can be caused by chemotherapy. 

“I will be back, you know,” Roberts said during her last broadcast Aug. 30, departing ahead of schedule to visit ailing mother Lucimarian Tolliver, who died the next day. “This is just see you later. See you soon. I will get back as fast as I can.”

Roberts’ absence comes as GMA continues to challenge NBC’s Today in the morning news race. Notching victories not seen in two decades, GMA won premiere week of the 2012-13 season (Sept. 24) in adults 25-54 and total viewers, besting Today by significant margins.

In the key demo, the ABC broadcast topped Today by 254,000 viewers (1.937 million over 1.683 million). And in total viewers, GMA won by a margin of 808,000 viewers (4.957 million over 4.149 million). GMA has not won a premiere week by either measure in 20 years, last topping in total viewers at the start of the 1992-93 season and winning the demo for 1991-92.

Year over year, GMA’s premiere week was up 2 percent in total viewers and 4 percent in adults 25-54. Today dropped 21 percent in viewers and 28 percent in the demo.

E-mail: Marisa.Guthrie@thr.com; Twitter: @MarisaGuthrie