Adam Kinzinger says he should've been 'worried' at how easily he was able to reach Marco Rubio before endorsing him in 2016: 'No presidential candidate should be that available'

• In Adam Kinzinger's new book, he recounts some key moments from the 2016 GOP presidential primaries.
• Kinzinger backed Florida Sen. Marco Rubio after former Florida Gov. Jeb Bush left the race.
• He said he should've been "worried" at how easy it was to text with Rubio about the endorsement.

As the 2016 Republican presidential field took shape, then-Rep. Adam Kinzinger made the decision early-on to get behind former two-term Florida Gov. Jeb Bush, who at the time was widely seen as the favorite for the nomination.