he told the Tulsa World. "His life indicates he does not have a commitment to the character traits necessary to be a great president."

Coburn added that Gingrich, who has been married three times and divorced twice, "doesn't know anything about commitment to marriage."

The former speaker is expected to announce a presidential exploratory committee Thursday.

Fox News had employed Gingrich as a paid contributor, but suspended him and former Sen. Rick Santorum (R-PA) Wednesday.