Fredreka Schouten

USA TODAY

WASHINGTON — A Facebook co-founder is pledging to donate $20 million to Democratic groups to help stop Donald Trump.

Billionaire Dustin Moskovitz and his wife Cari Tuna said the Republican presidential nominee and his party are running a campaign "built on fear and hostility."

"If Donald Trump wins, the country will fall backward and become more isolated from the global community," they wrote. "This distinction is starkly caricatured by his #1 'policy' position: the literal building of a wall between us and our neighbor."

They said Democrats, by contrast, are offering a "vision of optimism, pragmatism, inclusiveness and mutual benefit." The two announced their intentions in a Thursday night post on Medium.

Half of the $20 million would go to the League of Conservation Voters and to a super PAC called For Our Future, launched this year by labor groups and Tom Steyer, a billionaire environmentalist and top Democratic donor.

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Moskovitz and Tuna said they also will donate to Democrat Hillary Clinton's campaign and to party committees working to elect Democrats to the House and Senate.

Moskovitz, Mark Zuckerberg's Harvard roommate, became one of the world's youngest billionaires by co-founding Facebook. The CEO of a start-up called Asana and a philanthropist with his wife, Moskovitz has mostly shied away from making political donations. This is the first major push from Moskovitz and Tuna into politics.

These donations, coming in the homestretch of the campaign, will push him into the top ranks of political givers in this election. Only two people have donated more to groups that publicly disclose contributions: Steyer, who contributed $38 million through the end of July, and Robert Mercer, a Republican-aligned hedge-fund manager who has donated a little more than $20 million. Mercer, an early backer of Sen. Ted Cruz's failed presidential bid, now supports Trump.

Million-dollar donors