About 20 demonstrators gathered Tuesday outside the North Shore estate of hedge fund billionaire Robert Mercer, decrying his funding of conservative causes and calling on the state and federal governments to raise taxes on the wealthy.

Holding a sign that read “Mercer Pay Your Taxes” in front of the Head of the Harbor home’s owl statutes, protesters from New York Communities for Change and a local anti-war group said they wanted the state to pass a “millionaire’s tax” and close what they called a loophole on high volume stock trades.

“Young people are moving out of the state. Poverty is at its highest level since 1959. Taxes are too high, while people who are richer don’t pay their fair share,” said Tamar Paoli, 25, an Elmont resident who works in marketing.

Mercer could not be reached for comment Tuesday.

Bill McNulty, 82 of East Setauket, a member of the North Country Peace Group, said Mercer “played a major role in bringing about the election of Donald Trump. We saw the corrosive and contaminating effect of dark money on politics.”

More than a dozen police officers from Suffolk County and Head of the Harbor closed off one lane of the road in front of the house to accommodate protesters. The demonstration, in pouring rain, lasted about half an hour.

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It was the second protest against Mercer in the past week. On Friday, about 60 people protested outside the East Setauket company Renaissance Technologies, where Mercer serves as co-CEO.

Recent news reports describe Mercer as a quiet but formidable presence behind Trump’s election victory and the shaping of his cabinet.

Mercer and his daughter Rebekah reportedly were key in getting Trump last summer to hire Steve Bannon and Kellyanne Conway as top campaign aides. Bannon and Conway are credited with helping Trump to his upset victory over Democrat Hillary Clinton.

Mercer has given millions of dollars to political action committees that back Trump and his policies.

According to media reports, Mercer also has been a major investor in the conservative news website Breitbart, which Bannon used to run.