Garrett Haake / NBC

Protesters marched down the beach in New York's Hamptons to demonstrate against the power of deep-pocketed donors over the political process.

SOUTHAMPTON, N.Y. – In one of the most sizable shows of force from protestors seen on the campaign trail in weeks, a group of more than 60 demonstrators – backed by air support in the form of a banner plane – staged a protest of Mitt Romney's third and final fundraiser here on Sunday.

The fundraiser, at the beachside home of billionaire industrialist David Koch, was to cap a day of fundraising in New York's tony Hamptons communities that could bring in millions of dollars for the campaign's "Victory" fund. It marked Romney's return to the campaign trail after a week of vacation at his summer home in New Hampshire.

Romney and his guests received a loud – and at times profane – welcome from dozens of protesters representing organizations from Occupy Long Island to Greenpeace, which largely blocked a section of Meadow Lane to shout, "Shame on You!" (and unprintable variants thereof). The protesters waved signs at those who attended the back-to-back fundraisers hosted by Clifford Sobel, the former U.S. ambassador to Brazil, and later, by Koch.

It was Koch, whose net worth Forbes magazine pegs at $25 billion, who drew most of the protesters’ ire. Holding signs that compared the fundraiser's reported ticket price of $50,000 to their annual salaries or even life savings, the protesters decried the power of donors like Koch and his allies over American politics.

When local law enforcement officially cleared the protest, the demonstrators decamped from the street and – in one of the strangest visual moments of the campaign – marched nearly a mile down the beach to Koch's house.

Accompanied by a bass drum, horns and even a tenor saxophone, the ragtag band arrived at the stretch of beach behind Koch's house after a 20-minute walk, where roughly a dozen police, Secret Service and Romney staffers stood on the dunes that marked the line of demarcation between the public beach and Koch's private land, and told the protesters they could go no further.

And so they stayed - chanting, singing, and waving signs as a plane buzzed overhead, pulling a banner that read, "Romney has a Koch Problem. MoveOn.Org." While some protestors shouted obscenities as the security watching them from the dunes above (and from a Coast Guard vessel off the coast), this reporter saw no direct confrontations between protestors and authorities.

The climax of the protest event came when the saxophonist, David Intrator, 55, of New York City, led the protesters in a spotty rendition of "The Star-Spangled Banner," which most of the group joined, though some continued to chant slogans as they sang.