TALLAHASSEE, Fla. — Saying that his current relationship with Florida A&M University President Elmira Mangum is “broken and irreparable,” the chairman of the university board stepped down from his post on Friday.

Rufus Montgomery, an alumnus and a successful lobbyist in Georgia, notified other university trustees of his decision in a brief statement. Montgomery will remain on the board.

His decision to give up his position as chairman comes a day after trustees held a chaotic emergency meeting and almost voted to fire Mangum from her $425,000 a year job. Trustees deadlocked 6-6 on one vote.

The vote followed allegations about expensive repairs at Mangum’s university-owned home and improper bonuses for a top employee. Mangum has denied doing anything wrong and has accused some trustees of being on a “witch hunt.”

But Mangum has had a stormy tenure for most of her     nearly 18 months, including several notable clashes with Montgomery. Earlier this year Mangum hung up on Montgomery during an apparently testy phone call. She wound up writing a memo accusing Montgomery of harassment and violating university employee rules.

In his statement to trustees, Montgomery said when he was chosen as chairman he expected trustees to work together to hold Mangum accountable. But he said that “has not materialized and is not likely to occur with the current board.”

He added that “successful navigation” of challenges facing FAMU requires an “effective working relationship between the board chair and the university president.

“The current relationship is broken and irreparable,” Montgomery wrote. He also contended in his statement that, “I have consistently put FAMU first.”

FAMU, located near the state Capitol, is the state’s only public historically black university. Mangum was hired last year as a “change agent” who could help FAMU restore its reputation following a tumultuous period that included the November 2011 hazing death of band member Robert Champion of Decatur, Georgia. Former FAMU President James Ammons abruptly resigned in 2012 amid the fallout over Champion’s death. The university has also had problems with finances and audits that led to investigations and firings.

Mangum, however, embarked on a series of hiring and management decisions that drew criticism from alumni and trustees. A FAMU vice president under Mangum hired a special assistant who had previously pleaded guilty to financial aid fraud and was sentenced to three years of probation.

Mangum’s decision to name former NFL star tight end Kellen Winslow to run the athletics department ended quickly after he resigned in December 2014. Winslow drew criticism after he fired the school’s football coach during homecoming week.