At least one Koch brother has signed on to Donald Trump's presidential campaign by agreeing to host a $2,700-per-person fundraiser in his Cape Cod home.

Bill Koch, the 74-year-old founder of Oxbow Carbon, will host the event at his home in Oyster Harbors, Mass., on Saturday. Guests will include Republican National Committee Chairman Reince Priebus and former Massachusetts Sen. Scott Brown, according to a flier for the event, as well as Trump finance leads Steven Mnuchin and Lewis Eisenberg. Donation levels begin at $2,700 for individuals and run as high as $100,000 per couple.

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Koch is not as well known as his two brothers, Charles and David, and is not involved with their network of politically active groups. He left his family's largest business, Koch Industries, after bringing a lawsuit against the company and agreeing to a settlement in 2001.

Charles and David, known largely for their support of drug legalization and less border security, have said they do not support Trump. But they have committed to spending millions on House and Senate races around the country through a network of activist groups, which are run mainly under the auspices of Freedom Partners and Americans for Prosperity.