RICHMOND, Va. — A noted political scientist joined one of Senator Allen’s former college football teammates in claiming the senator used a racial slur to refer to blacks in the early 1970s, a claim that Mr. Allen dismisses as “ludicrously false.”

One of Virginia’s most-quoted political-science professors and a classmate of Mr. Allen’s in the early 1970s, Larry Sabato said in a televised interview Monday that Mr. Allen used the epithet.

Mr. Sabato’s assertion came on the heels of accusations by a radiologist who was a tight end and wide receiver for the University of Virginia in the early 1970s when Mr. Allen was quarterback, Dr. Ken Shelton. He said Mr. Allen not only used the N-word frequently but also once stuffed a severed deer head into a black family’s large mailbox.

Mr. Allen’s campaign released statements from four other ex-teammates defending the senator and rejecting Dr. Shelton’s claims.

An Allen strategist, Christopher LaCivita, said Messrs. Allen and Sabato were not friends nor did they associate with each other in college.

“Larry is obviously relying on words he heard from someone else,” he said. “We believe it’s completely inaccurate.”

The director of the University of Virginia Center for Politics, Mr. Sabato would not tell the Associated Press how he knew Mr. Allen used the N-word. He told Chris Matthews on MSNBC that he did not know whether it was true that Mr. Allen used the word frequently while in college.

“I’m simply going to stay with what I know is the case, and the fact is he did use the N-word, whether he’s denying it or not,” Mr. Sabato said.

Mr. Allen, a Republican, has been mentioned as a possible presidential candidate in 2008. Questions about racial insensitivity have dogged him during his re-election bid against Democrat Jim Webb.

Mr. Allen’s use of the word “macaca” in referring to a Webb campaign volunteer of Indian descent in August prompted an outcry. The word denotes a genus of monkeys and, in some cultures, is considered an ethnic slur. But the senator insisted that he did not know that and had simply made up the word.

Mr. Allen vehemently denied that he used the N-word.

“The story and his comments and assertions in there are completely false,” Mr. Allen said during an interview with AP reporters and editors. “I don’t remember ever using that word, and it is absolutely false that that was ever part of my vocabulary.”

Dr. Shelton said Mr. Allen used the N-word only around white teammates.

Dr. Shelton said the incident with the deer head occurred during their college days when he, Mr. Allen, and another teammate who has since died were hunting on a farm the third man’s family owned near Bumpass, Va., 40 miles east of the university.

Dr. Shelton said Mr. Allen asked the other teammate where black families lived in the area, then stuffed a deer’s head into the mailbox of one of the homes.

“George insisted on taking the severed head, and I was a little shocked by that,” he told the AP. “This was just after the movie ‘The Godfather’ came out with the severed horse’s head in the bed.”

Dr. Shelton said he came forward because of Mr. Allen’s presidential prospects and the “macaca” incident.

“When I saw the look in his eye in that camera and using the word ‘macaca,’ it just brought back the bullying way I knew from George back then,” he said.

Dr. Shelton’s claims came a week after a debate in which Mr. Allen bristled at questions about his Jewish ancestry. Mr. Allen later acknowledged publicly for the first time that his grandfather, a prisoner in a Nazi concentration camp, was Jewish, and on Monday, he said both his maternal grandparents were Jews.

Explaining his initial reaction, Mr. Allen has said his mother swore him to secrecy when she told him about his ancestry last month.