For how long can a Senator be absent?
There is no time limit on absences.
In 1964, California Democrat Clair Engle, whose bout with brain cancer left him unable to speak, was wheeled into the Senate to vote for the Civil Rights Act. Engle pointed to his eye and tried to mouth “aye.”
Some senators have been away from the chamber for years. Karl Mundt, R-S.D., suffered a stroke in late 1969 and refused to resign and allow a replacement to be named. He held the seat until January 1973. So he was absent for more than 3 years.
>>For how long can a Senator be absent?
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However long he/she wishes. Remember Rubio last term was absent for a large part because according to him, he found the Senate “boring”.
Then he was re-elected.