It's been a week of shakeups in the GOP presidential primary race. Just days before South Carolina's Jan. 21 primary, former Utah Gov. Jon Huntsman and Texas Gov. Rick Perry ended their campaigns. Then a bombshell dropped on Newt Gingrich's campaign as his ex-wife aired grievances in a televised interview. And another revelation: Iowa's GOP says Mitt Romney was not the winner of its caucuses after all. NPR's Ron Elving and Ken Rudin, on the road in Oklahoma, discuss the shifting political landscape heading into this weekend's vote.