By Liam Buckler & S P Jones Donald Trump’s battle with Joe Biden for the presidency is being seen as a contest over who “is more senile” according to experts, who today warn his popularity indicates a loss of faith in their leaders among US voters. The former president is now up against ex-U.N Ambassador Nikki Haley, after Florida Governor Ron DeSantis withdrew from the race and grudgingly backed Trump on Sunday. However, questions have been raised about the 77 year old’s “mental fitness” following a series of gaffes at his Iowa campaign rally. Trump was caught out confusing Nancy Pelosi with …