US First Lady Dr Jill Biden on Monday termed "ridiculous" a proposal from Republican presidential aspirant Nikki Haley that candidates over the age of 75 should undergo a mental competency test. "Ridiculous," Dr Biden told CNN in an interview when asked about such a proposal from Indian American Haley, who announced her presidential run on February 14. Haley's proposal has caught national attention, but she has been slammed by leaders in both the Republican and the Democratic parties.