WASHINGTON — With a new promise of $20 million to help defeat Donald Trump, billionaire Facebook co-founder Dustin Moskovitz becomes one of the top Democratic donors of the election. The Silicon Valley entrepreneur calls the Republican presidential candidate dangerous and divisive and says his appeal to Americans who feel left behind is “quite possibly a deliberate con.”

By contrast, Moskovitz says, Democrats and their nominee, Hillary Clinton, are “running on a vision of optimism, pragmatism, inclusiveness and mutual benefit.”

Trump has struggled to gain traction among the tech elite, even though Republicans have worked for years to strengthen the party’s relationship with the industry.

Oracle co-founder Larry Ellison gave $5 million to a super political action committee backing Republican Florida Sen. Marco Rubio in the primary.

One of the few tech leaders to warm up to Trump is PayPal co-founder Peter Thiel, who spoke at the Republican National Convention in Cleveland and was a Trump delegate.

Yet the billionaire who pumped more than $2.4 million into efforts to elect Republican presidential candidate Ron Paul four years ago hadn’t written the Trump campaign so much as a $201 check as of July 31, records show.

Moskovitz wrote about his planned Democratic contributions in a Thursday night posting on the website Medium titled “Compelled to Act.” Until now, Moskowitz had made only one federal campaign contribution, $5,200 in 2013 to Democrat Sean Eldridge. The husband of another Facebook co-founder, Eldridge unsuccessfully ran for a New York congressional seat.

Moskovitz and Tuna also are giving directly to Clinton’s campaign and to party committees helping Senate and congressional Democrats.