It was Lloyd Bentsen who made the retort about Jack Kennedy to Dan Quayle in a debate.

Catholicism is, in my opinion, no longer an issue with the vast majority of Americans. I don't suppose Jewishness would be either. However, muslimism ... !

The charge was made that Biden plagiarized an article while in law school. Here is a Wiki article:

"Within days, it was also discovered that, while a first year law student at Syracuse Law School, Biden had plagiarized a law review article in a class paper he wrote. Though the then-dean of the law school, as well as Biden's former professor, played down the incident of plagiarism, they did find that Biden drew "chunks of heavy legal prose directly from" the article in question. Biden said the act was inadvertent due to his not knowing the proper rules of citation, and Biden was permitted to retake the course after receiving a grade of F, which was subsequently dropped from his record."
http://en.wikipedia.org/wiki/Joe_Biden