Loudoun Board of Supervisors Chair Scott K. York shown in September 2008. (Katherine Frey/The Washington Post)

In an unexpected announcement Wednesday, longtime Loudoun County Board of Supervisors Chairman Scott K. York (R-At Large) said that he will not seek a fifth term in office this November.

The statement marked a sharp pivot from York’s announcement last year that he would pursue reelection. York, who has led the county board for 15 years and previously served as the Sterling district’s supervisor, shared his change of heart before his colleagues and the public at a county Board of Supervisors meeting Wednesday.

York did not offer details about what prompted his reversal, but told The Post that he had put much thought into what he wanted to do during the coming years.

“It just didn’t include being chairman for another four years,” he said. “After a lot of discussions with my wife, and careful consideration, I just made a decision that’s best for me and my family.”

For the remainder of his term, he said, he will focus on leading the board during the upcoming fiscal 2016 budget discussions and focusing on critical issues such as transportation and economic development.

Though he won’t be running in the November race himself, York said he still plans to play an active role in the upcoming elections “in supporting good candidates.” He added that he hopes one of his fellow board members will seek the Republican nomination for chairman.

York, a Republican who has previously served as an independent, would have faced a primary challenge from within his own party this year: Leesburg attorney Charles King, who has represented Loudoun County Supervisor Eugene Delgaudio in several controversial legal matters, recently told the Loudoun Times-Mirror that he intended to run for chairman as a Republican.

Democrat Phyllis Randall, a member of Virginia’s Fair Housing Board and vice chairperson of the state Board of Corrections, has announced that she will also compete for York’s vacated seat in November. Randall, a Loudoun resident of more than 20 years, previously ran for the Broad Run district supervisor seat in 2007 and lost to Republican Lori Waters.

The upcoming county election includes all nine seats on the county Board of Supervisors, as well as Loudoun’s constitutional officers — including sheriff, commonwealth’s attorney, clerk of the circuit court, commissioner of the revenue and treasurer.