Amid criticism even from his own supporters, Ben Carson has offered a bizarre explanation on why he decided to endorse Donald Trump for the U.S. presidency.

Speaking on Newsmax TV on Monday, Carson said even if Trump turned out to be a lousy president, he'll only be in office for four years.

"Even if Donald Trump turns out not to be such a great president, which I don't think is the case, I think he's going to surround himself with really good people. But even if he didn't, we're only looking at four years as opposed to multiple generations and perhaps the loss of the American dream forever," Carson said.

The former Republican presidential candidate said his decision was "practical" rather than "personal" and he would have preferred another candidate, the Towleroad news website reported.

"I have to look at what is practical. I didn't see a path for (John) Kasich, who I like, or for (Marco) Rubio, who I like...So I have to look at what is practical and what is going to save this country and the American dream for the next generation...Is there another scenario that I would have preferred? Yes — but that scenario isn't available."

Carson also disclosed that Trump—who once labelled him "pathological" and compared him to a child molester—has offered him a role in a Trump administration but wouldn't say if it was a cabinet position.

"He [Trump] will surround himself with very good people...I will be doing things as well...certainly in an advisory capacity...We haven't hammered out all of the details but it is very important that we work together in this country...Again, I'm not going to reveal any details because all of this is still very liquid," Carson said.

Carson's decision to endorse Trump divided his supporters, with some expressing shock and anger over the move, The Hill reported.

"Can't believe you chose to support the one candidate who mocks God and is definitely not a Christian. Very disappointed in you and have lost much respect," one supporter wrote on Carson's Facebook page on Friday.

"I voted for you even though I knew you wouldn't win my area's primary," another wrote. The supporter added that it was "confusing why you would support a person who mocks God by saying he doesn't have to ask for forgiveness and disparages minorities including the disabled and women."

"Honestly I feel used," another former supporter wrote. "I feel like you sold out. You speak of Party as if it has relevance in the kingdom. I am hurt and feel like you have used the flag of Christ to sell out for political gain. I will never support Donald Trump."