A Republican candidate for the Fairfax County Board of Supervisors died Sunday after experiencing a heart attack at the end of a day of campaigning, his family and friends said.

Republican Paul Bolon, 69, complained of chest pains while walking through the county’s Providence District to introduce himself to voters, said Andrea Bayer, a school board candidate who was with Bolon Sunday. He was taken to Inova Fairfax Hospital and died a few hours later, his family said.

“We’d been knocking on doors all day,” Bayer said Tuesday. “But we weren’t doing any hills, and it was cool outside. We were laughing.”

Bolon, a retired manager at the federal Occupational Safety and Health Administration, was competing in the November elections against Democrat Dalia Palchik for the county board seat being vacated by Supervisor Linda Q. Smyth (D).

In a June interview, Bolon said he planned to advocate for more schools in the northeast Fairfax district and hoped to eliminate wasteful spending.

“We’re beginning to look like San Francisco,” he said at the time. “Our middle-class has hollowed out.”

Palchik called Bolon a fair-minded opponent.

“We were both looking forward to honestly debating important issues, at a time of such bickering and division,” Palchik said in a statement.

Tim Hannigan, the chairman of Fairfax County’s Republican Committee, said the party will seek a replacement candidate for the Providence seat.

“Paul Bolon was a great candidate,” Hannigan said in a statement. “A professional economist, he brought a clear-eyed, analytical perspective to issues facing our county.”