On May 6, Sen. Susan Collins , a Republican from Maine, revealed that she’s had a condition called essential tremor throughout the duration of her nearly 30-year Senate career and that she takes medication for it. “I have had it for the entire time that I have served in the United States Senate,” Collins, 73, told News Center Maine . “It has absolutely no impact on my ability to do my job or on how I feel each day.” Collins recently announced in a video that she is running for a sixth term, and online comments called attention to the shakiness in Collins’ hands, voice, and head. Collins' announcement comes as her Senate race is one of the most closely watched of this year's midterm elections , one in which concerns about her age is a factor for some voters. Last week, Maine Gov. Janet Mills, 78, suspended her Senate campaign , effectively ceding the fight for the Democratic nomination to political newcomer Graham Platner, who is 41.…