The embattled former chancellor of the Virginia community college system, found to have plagiarized parts of his doctoral thesis, unexpectedly withdrew his bid for reappointment today minutes before state officials met behind closed doors and selected another man for the job.

Dana B. Hamel's decision surprised members of State Board of Community Colleges, who described him as a front-runner on the list of three candidates for the job.

"Hamel had enough votes (on the board) to be elected," said Doreen Williams, a state board member from Fairfax County. "But he would have the problem of coming into the system without the support of everyone on the board. There are those of us who would not have voted for him."

Hamel had been endorsed for the position by several of the state's leading political figures, including former governor Mills E. Godwin, who named Hamel to the chancellorship in 1966. He served until 1979 when he was forced to resign after reports of financial mismanagement in the system.

After Hamel withdrew from the competition today, the board named Johnas F. Hockaday, 54, a North Carolina educator, to be the new chancellor. The board, which held a three hour-executive session, also created a new $55,000-a-year deputy chancellor's position for the third candidate, Don Puyear, 50, president of Central Community College in Lynchburg. Board members said they have not decided the duties of the deputy chancellor, but established a committee to help mold the office and its responsibilities.

In a short statement hand-delivered today to the board, Hamel said he was withdrawing as a candidate because "another opportunity which is very attractive will be available to me in the next two to three weeks." He said he was "not at liberty to discuss any of the details of this position."

Hamel, who has been serving as director of special academic programs at Virginia State University in Petersburg, said in an interview the controversy that had clouded his nomination played no role in his decision to step out of the competition.

The board unanimously elected Hockaday to the $61,880-a-year chancellorship to replace James H. Hinson Jr., who resigned from the position to become president of the Tallahassee Community College in Florida. A soft-spoken North Carolina native, Hockaday was selected on the basis of his administrative skills, said Francis T. West, vice chairman of the board. Hockaday has been president of Central Carolina Technical College in Sanford, N.C., since 1979.

Puyear, the new deputy chancellor, has been a president of three Virginia community colleges since 1967 and is now in his third term as president of Central Virginia.

The controversy over Hamel's candidacy focused on disclosures that parts of his 1962 doctoral thesis at the University of Cincinnati had been lifted from earlier works on the same subject. The university faculty eventually concluded that Hamel's plagiarism was not intentional, but it did attach a cover note to his dissertation at the school noting its similarity to earlier works.

Despite that controversy, Hamel maintained a strong backing from many state officials who credit him with building up Virginia's community college system that includes 23 campuses.