Billionaire Democratic donor Tom Steyer, who is leading an initiative to encourage Democratic lawmakers to impeach President Donald Trump, announced Monday that he will not run for political office in 2018, but will invest millions of dollars into a campaign to help Democrats win the majority in the House in the November mid-term elections.

At a news conference in Washington, D.C., Steyer said, “I’m willing to do whatever it takes to help save our country. And I believe the most important task for me, the task which I feel called to do, is organizing and mobilizing America’s voters.”

Steyer, a businessman and environmentalist, said he is not going to run for office in 2018 because “that’s not where I can make the biggest difference.”

Instead, Steyer plans to spend at least $30 million funding his advocacy group, NextGen America, in an attempt to motivate millennials in 10 states to vote. In order for the Democrats to win the majority in the House in 2018, they must flip a minimum of 24 seats.

Steyer has long considered running for political office. In 2016, he decided against a bid to replace retiring Sen. Barbara Boxer (D-Calif.) and he had been rumored to be weighing a run for governor of California or a primary challenge to Sen. Dianne Feinstein, D.-Calif. this year.

As one of the wealthiest Democratic donors in American politics, Steyer invested more than $91 million during the 2016 campaign, funding candidates, super PACs and NextGen America.

Steyer is currently best known for his $20 million “Need to Impeach” advertising campaign in which he implores Congress to impeach Trump.