Ex-White House physician Ronny Jackson has said he is 'convinced' Joe Biden is not fit for office following his latest memory slips – hours after Donald Trump accused his Democratic rival of suffering from 'dementia'.Jackson, who once claimed Trump could live to 200 years old and is now running for Congress as a Republican, said Tuesday that 'as a physician' he believes Biden does not have the 'mental capacity' or 'cognitive ability' to run the country. 'I'm pretty familiar with what it takes both physically and cognitively to do that job and what the demands of that job are,' Jackson told reporters on the call organized by the Trump campaign, according to the New York Post.His comments come one day after Biden's latest gaffe where he appeared to forget Mitt Romney's name calling him the 'senator who was a Mormon' and said he himself was 'running for Senate'.Trump, who has repeatedly attacked Biden's cognitive abilities and nicknamed him 'sleepy Joe', jumped onto the latest mishaps tweeting Tuesday morning that his rival has 'dementia'. Jackson, 53, who has multiple photos of himself with Trump and the Trump family on his congressional campaign's Facebook page, joined in the debate about Biden's mental competence on Tuesday's call.The Republican nominee for Texas's 13th congressional district said he was 'concerned' about Biden's mental capacity to be president. 'As a citizen, not as a candidate running for Congress, but as a citizen of this country, I've watched Joe Biden on the campaign trail and I am concerned and convinced that he does not have the mental capacity, the cognitive ability, to serve as our commander-in-chief and our head of state,' he said. Jackson said he wasn't going as far as to accuse the Democrat of having dementia. 'I'm not trying to remotely diagnose him with anything,' he said. Share this article Share 'I've not accused him of having Alzheimer's or anything of that nature.'Jackson worked as Physician to the President under both Barack Obama and Trump, before he was nominated to serve as the Secretary of Veteran Affairs in 2018 - a nomination he later stood down from amid accusations of drunken behavior.Prior to this he also worked in the White House medical unit under the George W. Bush administration. Jackson admitted on the call that he never evaluated Biden as a patient or provided him care when Biden was Vice President and he worked as a physician for the Obama administration. The Navy rear admiral went on to say Biden's mistakes are not the 'typical gaffes' he has seen of him over the years. 'They're not the typical gaffes. He routinely gets in the middle of a thought and then loses his train of thought and then he can't re