Parents of GOP Senate candidate Kevin Nicholson gave max donations to Democratic Sen. Tammy Baldwin

GOP Senate candidate Kevin Nicholson turned his back not just on the Democratic Party when he switched political affiliations more than a decade ago.

Nicholson also split politically with his parents.

Federal records show that Michael and Donna Nicholson, parents of the candidate, both gave the maximum $2,700 donation in December to U.S. Sen. Tammy Baldwin, the Wisconsin Democrat Nicholson hopes to unseat later this year.

"My parents have a different worldview than I do, and it is not surprising that they would support a candidate like Tammy Baldwin who shares their perspective," Nicholson said in a statement. CNN was the first to report the donations.

Nicholson, a Delafield businessman and U.S. Marine veteran, is squaring off against state Sen. Leah Vukmir, a Brookfield Republican, in the GOP primary in August.

Joshua Karp, a spokesman for American Bridge, a liberal super PAC backing Baldwin, chided Nicholson over the lack of family loyalties.

“Even his parents can’t hold their nose and support this guy – and that tells you everything you need to know about him," Karp said.

RELATED: Bice: Kevin Nicholson’s mother donates to Democrats — and that includes Tammy Baldwin

Donna Nicholson has been a longtime Democratic financial supporter, having previously given $441 to Baldwin and another $500 to former U.S. Sen. Russ Feingold of Wisconsin. She chipped in $500 to Democratic presidential nominee Hillary Clinton.

More recently, she has written checks to such Democratic candidates as U.S. Rep. Mark Pocan from Wisconsin and U.S. Sens. Al Franken of Minnesota and Tim Kaine of Virginia in the past year.

Nicholson's mother is also a frequent donor to Democracy for America, a liberal political action committee that has endorsed Randy Bryce, a Democrat hoping to challenge House Speaker Paul Ryan, a Wisconsin Republican.

Nicholson's parents can each give another $2,700 to Baldwin for the general election.

"I'm a conservative today not because I was born one, but because of the experience I earned as a Marine in combat, my experience as a husband and father, my choice to be a Christian, the schools I chose to attend and the decision to pursue the career that I have," Nicholson said in his statement on Tuesday.

"Regardless of who may disagree with my life decisions, I would not trade these experiences for anything, and they will always guide my views as Wisconsin's next U.S. senator."

The tension between Nicholson and his parents is nothing new.

In 2000, when Nicholson was the president of the College Democrats of America, he told the Journal Sentinel that his parents might not like it if he ran for office in Wisconsin.

"They're afraid of being found out as the only Democrats in Mequon," Nicholson said on Aug. 14, 2000.

Nicholson has acknowledged his past ties to the Democratic Party. There has been some dispute over when he changed political parties; he has said it was a gradual shift.

Contact Daniel Bice at (414) 224-2135 or dbice@jrn.com. Follow him on Twitter @DanielBice or on Facebook at fb.me/daniel.bice.