Former presidential hopeful Dr Ben Carson refused to state whether he believed the sexual assault allegations against Donald Trump, demanding a reporter's microphone be turned off when she questioned him about it.

The vocal Trump supporter appeared on MSNBC's Morning Joe show to discuss the presidential campaign in the wake of the accusations, as well as finance and media bias.

As the conversation moved on to the women who accused Trump of groping them, Carson did not answer Katty Kay's question as to whether he thought the women were lying.

"No,no,no,no, stop stop stop stop - hey can you turn her microphone off please - turn her microphone off so I can talk," Carson said.

But host Joe Scarborough refused to turn Carson's microphone off and asked him to answer the question, responding: "No. No it's a simple question yes or no - do you believe these women are lying or not - nobody's trying to paint you as a bad guy, we just want an answer. Straight talk."

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Carson eventually responded to the question, stating: "It doesn't matter whether they're lying or not, what matters is that the train is going off the cliff - we're taking our eye off of that and we're getting involved in other issues."

He was interrupted by Kay, who said it did matter whether the women were lying, as the campaign was suggesting they were lying. "That's a huge issue," she said.

Republican Carson initially ran against Trump during primary season, quickly backing him after pulling out of the residential race and becoming one of the people the GOP nominee consults during his VP running mate selection process.

The retired neurosurgeon maintained his support of Trump, shying away from directly answering the question for the remainder of the interview - something that was criticised by Scarborough before the pair engaged in a debate about whose side the media was on.