In the tweet, Welch shared a link to a story about legislation he has introduced that would immediately provide back pay to federal workers who have been required to work during the partial shutdown, now in its 32nd day.
Welch sent a follow-up tweet later Tuesday in which he apologized for his statement.
“Sincere apologies,” he said in the tweet. “Nothing worse in the history of our country than the brutal inhumanity of the horrible, relentless, and savage infliction of involuntary servitude-slavery- on millions of people whose freedom was denied. Nothing.”