Facebook co-founder Dustin Moskovitz is giving a second round of contributions to help make Hillary Clinton president.

"The events of the past few weeks have only deepened my conviction that Hillary is the best choice for America," he wrote.

In a Medium post, Moskovitz said he will donate $5 million to the pro-Clinton super PAC Priorities USA and as much as $3 million to other political action groups.

Moskovitz will also give up to $7 million to nonpartisan efforts to register new voters and encourage Americans to go to the polls.

The billionaire's announcement comes amid the worst crisis yet in the campaign of Republican nominee Donald Trump.

On Saturday, Trump offered a rare apology for the crude and sexist language he used to describe women in a 2005 tape, which was recorded on a hot mic and revealed to the public on Friday. CNN's KFile later reported that Trump had lewd conversations with radio host Howard Stern over the course of 17 years; in one, Trump agreed to Stern's description of Ivanka Trump as a "piece of ass."

Earlier in the week, Trump was criticized for doubling down on claims that the wrongfully convicted -- and later exonerated -- "Central Park 5" were guilty.

Moskovitz and his wife, Cari Tuna, made a surprise $20 million donation to Democratic political efforts back in September.

"The Democratic Party, and Hillary Clinton in particular, is running on a vision of optimism, pragmatism, inclusiveness and mutual benefit," the couple wrote at the time. "For the first time, we are endorsing a candidate and donating. We hope these efforts make it a little more likely that Secretary Clinton is able to pursue the agenda she's outlined."

In September, the couple gave to the Hillary Victory Fund, the For Our Future PAC and a number of other groups.

This time, Moskovitz said he hopes his donation will help engage independent and millennial voters -- many of whom could still be undecided. Clinton has recently seen a bump in support from both independent and young voters. The significant donation from Moskovitz could help continue that trend.

The second presidential debate will take place on Sunday.