Nikki Haley: leaders should release tax returns and prove mental competency

Comments by Republican believed to hold presidential ambitions questioning Biden's mental health could also apply to Trump

The former Trump cabinet member Nikki Haley was accused of ageism, as well as a startling lack of awareness about senior figures in her own party, after questioning Joe Biden's mental health and suggesting there should be some sort of cognitive test" for office holders above a certain age".

Haley made the remarks in an interview with the Christian Broadcasting Network - a conservative outlet founded by and often featuring the televangelist Pat Robertson, who turned 91 last March.