When Gary got back in the race in Dec. '87 he jumped to the lead in the polls. After a week of non-stop repetition of the Rice story, we actually went UP in the polls.
So, in order to smear him some more the MSM started a story that he was receiving "illegal" campaign contributions:
http://select.nytimes.com/gst/abstract.html?res=FB0711F63F580C728EDDA80894D0484D81&n=Top%2fReference%2fTimes%20Topics%2fSubjects%2fE%2fEthicsJanuary 21, 1988
and preferential treatment of creditors:
http://select.nytimes.com/gst/abstract.html?res=FB0716FD3D590C778EDDA80894D0484D81&n=Top%2fReference%2fTimes%20Topics%2fSubjects%2fE%2fEthicsJanuary 24, 1988
The cumulative affect of these stories, timed just before the Iowa caucuses, left such a cloud over Hart's '88 campaign that he couldn't overcome it, despite the fact that the FEC found no impropriety involved.
Hart never went back to the Senate because he felt that serving two terms was enough. He didn't want to be a career senator. He was up or out of Washington in '88.
Thomas Jefferson, Hart's hero, was an introvert as well.
So what?