Steve Krakauer at The Resurgent, has listed the 31 GOP governors and their position on Trump. They've grouped them into four categories: Oppose Trump, On The Fence, Support The Nominee, Endorse Trump.
As of June 8, 2016:
Charlie Baker – Massachusetts – Baker says “I’m not going to vote for [Trump] in November.”
On The Fence
Matt Bevin – Kentucky – Bevin says he’s waiting until July and the nominee is official.
Larry Hogan – Maryland – Hogan says he has no plans to endorse anyone.
Rick Snyder – Michigan – Snyder says he has no plans to endorse Trump, and “I’ve stayed out of the whole thing, and I’m going to continue to.”
Susana Martinez – New Mexico – Martinez won’t decide what she plans to do until she meets with Trump personally, which is happening soon.
John Kasich – Ohio – Kasich is in no rush, and has not said whether he’ll support Trump.
Dennis Daugaard – South Dakota – When it comes to supporting Trump, Daugaard says “I’m not there.”
Bill Haslam – Tennessee – Haslam has been critical of Trump, and says he’s waiting on a personal meeting with him.
Support The Nominee
Doug Ducey – Arizona – Ducey says he’ll back the nominee.
Asa Hutchinson – Arkansas – Hutchinson endorsed Rubio in the primary, but now says he’ll support Trump.
Nathan Deal – Georgia – Deal says he’ll support the nominee, but not everything he does or says.
Butch Otter – Idaho – Otter endorsed Kasich, but says “I’m all in, whoever gets the nomination.”
Bruce Rauner – Illinois – Rauner is somewhat in the middle of “On The Fence” and “Support The Nominee.” He has said he’ll back whoever the nominee is, but has no plans to endorse or even attend the convention.
Mike Pence – Indiana – Pence endorsed Cruz, but now says he’ll support Trump as the nominee.
Terry Branstad – Iowa – Branstad says he underestimated Trump, never thinking he had a shot, butwill now support him.
Sam Brownback – Kansas – Brownback says he’ll support the nominee.
Pete Ricketts – Nebraska – Ricketts says he’ll support the nominee (his parents led an effort to stop Trump).
Pat McCrory – North Carolina – McCrory says he’ll support the nominee, but didn’t endorse in the primary and doesn’t plan to.
Jack Dalrymple – North Dakota – Dalrymple says he’ll support the nominee, but when asked if he’d endorse Trump, he said, “I’m pretty much down to one choice, aren’t I?”
Nikki Haley – South Carolina – Haley said recently she wouldn’t consider being Trump’s running mate, but did say she’d support him as the nominee.
Greg Abbott – Texas – Abbott had endorsed Cruz, but now says he’ll support Trump as nominee.
Gary Herbert – Utah – Herbert says he’ll back the nominee.
Matt Mead – Wyoming – Mead says the way Trump has been is “not the way to go about” winning, but that he’d support him as nominee.
Robert Bentley – Alabama – Bentley initially endorsed Kasich, but has now fully endorsed Trump.
Rick Scott – Florida – Scott endorsed Trump one day after he won Florida.
Paul LePage – Maine – LePage was an early endorser of Trump.
Phil Bryant – Mississippi – Bryant initially endorsed Cruz, but has now fully endorsed Trump.
Chris Christie – New Jersey – Christie was one of the first major politicians to endorse Trump.
Mary Fallin – Oklahoma – Fallin endorsed Trump, and said she’d consider being his VP.