Billionaire and Democratic donor Tom Steyer went from financing climate change activism and Trump impeachment efforts to running a liberal campaign for president in 2020, and has had some limited success trying to break through in the polls thanks to his large advertising expenditures.

Here are five things to know about the 62-year-old as the 2020 presidential election cycle is officially underway.

1. He's the poorest billionaire in the presidential field

Steyer is one of three billionaires seeking the White House in 2020, along with President Donald Trump and former New York City Mayor Michael Bloomberg.

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But Steyer's $1.6 billion fortune, according to Forbes, is just a fraction of Trump's $3.1 billion net worth. Bloomberg, however, is richer than both Trump and Steyer combined, many times over, with a $53.4 billion net worth, according to Forbes.

2. He's a big left-wing booster

Like his fellow billionaire Bloomberg, Steyer has spent much of the past decade using his fortune to fund left-wing causes. One of his biggest accomplishments is the success of NextGen America, a grassroots organization targeted at organizing young people for progressive causes, like climate change.

Omnipresent on college campuses, NextGen America claims to have registered 1.3 million voters since 2013.

3. He almost always wears the same tie

One odd thing Steyer has become known for while on the campaign trail has been his red and black plaid tie, which he almost always wears.

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ABC's Zoheen Shah reported last year that Steyer gave former presidential candidate Andrew Yang, who became known for not wearing ties, the same tie that he always wears as a Christmas gift.

"Andrew, I notice you lack neckties. I'm here to help. Many happy returns of the day. Tom," read a note from Steyer that came with the tie, according to Shah.

4. He was one of the first to sign The Giving Pledge

The Giving Pledge is a commitment some of the richest people in the world have made to donate most or all of their fortunes to charitable causes before they die. Steyer and his wife, Kat Taylor, were among the first to sign the pledge in 2010.

Bloomberg also signed the pledge in 2010.

5. He was one of the first to call for Trump's impeachment

In October 2017, Steyer appeared in an ad launching the organization "Need to Impeach," which aimed to force Republican members of Congress to publicly say whether or not they would impeach Trump.

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"I'm Tom Steyer, and like you, I'm a citizen who knows it's up to us to do something. It's why I'm funding this effort to raise our voices together and demand that elected officials take a stand on impeachment. A Republican Congress once impeached a president for far less," Steyer said.

"People in Congress and his own administration know that this president is a clear and present danger who is mentally unstable and armed with nuclear weapons," he continued. "And they do nothing."