Donald Trump will be on Nantucket and Cape Cod this weekend for two high-dollar fund-raisers, including one at the Osterville home of prominent Cape Wind opponent Bill Koch.

The Republican presidential nominee will visit the island for an appearance that begins at 3 p.m. Saturday. Donors there will give at least $2,700. Couples who want to cochair the event must donate or raise $50,000. The event is at the home of Terri and Ron Weinberg.

At 6 p.m., Trump is scheduled to be back on the Cape at the Oyster Harbors home of Bridget and Bill Koch, where guests will give or raise between $2,700 and $100,000.

Members of the host committee for that event include radio host Howie Carr, former state treasurer Joe Malone, former US senator Scott Brown, and Cape & Islands District Attorney Michael O’Keefe .

Billionaire Bill Koch is a brother of Charles and David Koch, who have refused to use their powerful political organization to back Trump. Bill Koch was a major backer of the Alliance to Protect Nantucket Sound, which fought to stop a proposed offshore wind project.

Jim O’Sullivan of the Globe staff contributed to this article. Andy Rosen can be reached at andrew.rosen@ globe.com. Follow him on Twitter @andyrosen.