Fairfax County School Board Chairman Mary E. Collier, who three weeks ago cast the decisive vote to close Fort Hunt High School, yesterday survived an unprecedented challenge to her job by two county supervisors from her own political party.

The Fairfax Board of Supervisors agreed by a 5-to-2 vote to reappoint Collier, but supervisors of both parties said the dissenting votes -- by Republicans T. Farrell Egge of Mount Vernon and Elaine McConnell of Springfield -- set a dangerous precedent and threaten to politicize the School Board.

Egge, the newest member of the board and the supervisor who represents the Fort Hunt area, led the move to deny Collier another four years on the School Board.

"Given what has happened," he told the supervisors, "there is no way I could look my constituents in the eye and tell them I support the motion" to reappoint Collier. He said he believed the decision to close Fort Hunt, which has angered many residents of the area, was "unfair."

Although some Fairfax Republicans have attempted to make the Fort Hunt closing a major political issue, Egge was able to secure only McConnell's backing.

Two other Republican supervisors who have been critical of the closing, Board Chairman John F. Herrity and Supervisor Thomas M. Davis II, were out of the board room at the time of the vote.

Collier was saved by the board's four Democratic supervisors who joined Republican Supervisor Nancy K. Falck to support her reappointment. Supervisor Joseph Alexander, the board's senior Democrat, said he could not remember any previous challenge to a supervisor's school board appointee in his 22 years as a supervisor.

School Board members in Virginia are appointed and in Fairfax that gives each of the nine members of the Fairfax County Board the right to nominate a School Board member. "The School Board has to be allowed to use their individual judgment on these issues," Alexander said, "and I don't think there should be any political connotations at all."

Collier, who makes $5,500 as a School Board member and an additional $500 as chairman, was unavailable for comment yesterday.

Asked last week about rumors that some supervisors planned to oppose her, she replied: "I haven't heard that, but if it's true, it's very sad."

The decision by the School Board March 14 to close Fort Hunt High School capped months of frequently emotional debate over how to solve the problem of declining school enrollments in eastern Fairfax. The debate took on social and economic overtones, with the predominantly white and Republican Fort Hunt community pitted against the racially mixed and mostly Democratic Groveton area.

The School Board's decision to convert Fort Hunt into an intermediate school and send its 1,260 students to nearby Groveton High School this fall came on a 6-to-4 vote.

"I would not have voted against [Collier]," said Supervisor Davis who was out of the board room at the time. "Each of us is entitled to name our own School Board member," he said. "If you start messing with other board members' appointees. they'll start messing with your appointee." Herrity declined to comment.

Democratic Supervisor James M. Scott of Providence said he believed Egge's vote against Collier's reappointment was a signal that the right wing of the Republican Party was trying to pressure the School Board.

"You can understand Farrell's [vote]," he said. "He's gotten a lot of pressure from the right wing of the Republican Party. It's the far right of the Republican Party trying to exert control over School Board appointments and over School Board policy."

Benton K. Partin, head of the Fairfax GOP, telephoned at least one Democratic supervisor, threatening to challenge her reelection if her School Board appointee did not vote for reopening the Fort Hunt decision.

Scott warned that if the School Board were not insulated from partisan politics, "We're going to find that people like [newly named school superintendent Robert R.] Spillane are going to think twice about coming to Fairfax County."

Spillane recently resigned as head of the Boston schools to become head of the Fairfax schools.