Des Moines, Iowa (CNN) Billionaire Tom Steyer will not run for president in 2020, he told reporters here in Iowa on Wednesday, ending months of speculation that the Democratic donor would escalate his efforts to defeat President Donald Trump by attempting to take him on at the ballot box.

Steyer, a 61-year-old hedge fund manager, said he will instead focus on his efforts to take on Trump from the outside, namely through Need to Impeach, a group he founded after Trump's win in 2016 that looked to garner public support around impeaching Trump.

"Now the impeachment question has reached an inflection point," he said. "Therefore, I will be dedicating 100% of my time, effort and resources to one cause, working for Mr. Trump's impeachment and removal from office."

He added: "I am not running for president at this time. Instead, I am strengthening my commitment to Need to Impeach in 2019 until the House starts impeachment proceedings or Mr. Trump resigns."

Steyer, who spent about $120 million to influence the 2018 midterm elections, has been one of the Democratic Party's most prolific donors since leaving his hedge fund in 2012 to pursue political activism full time.

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