Kevin Nicholson, a Republican hopeful for the U.S. Senate from Wisconsin, speaks with reporters in Madison, Wis. (Scott Bauer/AP)

Kevin Nicholson, a Republican candidate for U.S. Senate in Wisconsin, is continuing a public feud with his parents, calling them politically intolerant in an opinion piece published Monday on the Fox News website.

Michael and Donna Nicholson made national headlines in February for giving $2,700 apiece, the maximum allowed under law — not to their son but to the Democratic incumbent in the race, Sen. Tammy Baldwin.

In his Fox piece, Kevin Nicholson called that “an intentional personal blow.”

“It was deliberate — and it is a true representation of the intolerance of a political philosophy that stands on the false platform of tolerance,” Nicholson said.

Nicholson said he felt compelled to speak out as the #WalkAway movement gains steam. The movement encourages people to speak out about why they left the Democratic Party.

“My decision to be a Democrat was never a decision. It was just expected of me. It was understood,” said Nicholson, who was elected National President of the College Democrats of America in 1999.

“While the Democrats’ influence over my political philosophy defined a few years in my late teens and early twenties, that influence could not withstand the test of life and experience that made me a conservative as an adult,” he said.

As he seeks a Senate seat, his parents, Nicholson said, have “turned their back on me, my wife, their grandchildren, and their extended family.”

Nicholson faces state Sen. Leah Vukmir in the Aug. 14 Republican primary.