Newt Gingrich, as Speaker of the House, was only two heartbeats away from the Presidency.
He is more than qualified.
And while not an Executive position, it did showcase a tragic flaw in Gingrich's ability to lead. After only four years with his Party still in power, his own members mutinied and forced him out. That's not exactly a ringing endorsement of his ability to lead.
Gingrich may have worked well with President Clinton, but he did not cut taxes, and he did not create a surplus as he is claiming. He only exacerbated the weakness that Republicans are best known for.
The government shutdown is a prime example of this. Not even John Boehner has shown as much weakness as Gingrich did that day.