What's behind Ben Carson's Trump meltdown?

Donald Trump has a Ben Carson problem.

The former presidential candidate and retired neurosurgeon has endorsed the billionaire Republican front-runner. But Carson's media appearances supporting Trump have been widely panned. Carson has been described as being the "worst surrogate ever" after the repeated missteps.

It started in an interview with "The View" when Carson struggled to explain his Trump endorsement and offered only a lukewarm defense when the reality TV star was accused of racism. He also disavowed Trump's tweets about Heidi Cruz.

In later interviews, Carson described Trump's poll numbers as horrible. He's suggested Trump read the Bible and pray more. He'scommented on Trump's Twitter habits.

Tim Miller, an anti-Trump Republican operative who formerly worked for Jeb Bush's campaign tweeted, "Is it possible that Ben Carson is secretly with us and is sabatoging Trump from the inside?"