Vermont Sen. Bernie Sanders announced Tuesday that he is running for president in 2020. His 2016 electoral campaign has reportedly reshaped the Democratic politics.

“Our campaign is not only about defeating Donald Trump,” the 77-year-old self-described democratic socialist said in an email to supporters. “Our campaign is about transforming our country and creating a government based on the principles of economic, social, racial and environmental justice.”

An enthusiastic progressive, democrat who encourages proposals ranging from Medicare for All to free college tuition, Sanders stunned the Democratic establishment in 2016 with his spirited challenge to Hillary Clinton. While Hillary became the party’s nominee, Bernie’s campaign helped lay the groundwork for the leftward lurch that has dominated Democratic politics in the Trump era.

But the thing to watch is whether he can stand out in a crowded field of Democratic presidential candidates who also embrace many of his policy ideas and are newer to the national political stage. That is very different from 2016 elections when he was Clinton’s lone progressive adversary.

Yet, there is no doubt that Sanders will be a formidable contender for the nomination by the Democrats. In 2016, he won more than 13 million votes and dozens of primaries and caucuses. He has opened his campaign with a nationwide organization and a proven small-dollar fundraising effort.

“We’re gonna win,” Sanders said in an interview on Tuesday morning.

And Sanders should be positioned really well to compete in the nation’s first primary in neighboring New Hampshire, which he won by 22 points in 2016. But he won’t have the state to himself.

Sen. Kamala Harris of California, another Democratic presidential contender, was in New Hampshire on Monday and said she would contest for the State. She also took a dig at Sanders.

“The people of New Hampshire will tell me what’s required to compete in New Hampshire,” she told shoppers at a bookstore in Concord. “But I will tell you I’m not a democratic socialist.”

Sen. Elizabeth Warren of nearby Massachusetts is scheduled to be in New Hampshire on Friday.

One of the biggest things to see in Sander’s campaign would be how he’ll compete against someone like Warren, who shares many of his policy goals. Warren has reportedly launched her campaign and has planned an aggressive swing through the early primary states.

Just after announcing her exploratory committee, Warren hired Brendan Summers, who managed Sanders’ 2016 Iowa campaign. Other staffers from Sanders’ first bid also have said they might consider working for other candidates in 2020.

The battle field for 2020 includes a number of other candidates who will likely make strong appeals to the Democratic base including Harris and Sens. Cory Booker of New Jersey, Amy Klobuchar of Minnesota and Kirsten Gillibrand of New York. The battle field also might grow more prominent, with a number of high-profile Democrats still considering presidential bids, including former Vice President Joe Biden and former Texas Rep. Beto O’Rourke.

As Sanders had been working to lay the groundwork for a second campaign for months, it was still not clear whether he will be able to expand his appeal beyond his mostly white base of supporters. In 2016, Sanders struggled to garner support from black voters, an issue that could become particularly pervasive during a primary race that could include several non-white candidates.

It should be reported here that last month he joined Booker at an event in Columbia, South Carolina, marking the Martin Luther King Jr. holiday. During the 2016 elections, Sanders lost the South Carolina primary, which features a heavily black electorate, by 47 points.

Sanders also has much pressures on him in the #MeToo era. Some of his supporters in 2016 were described as “Bernie bros” for the way they treated women. In the run-up to Sanders’ 2020 announcement, allegations emerged of sexual harassment of women by male staffers during his 2016 campaign.

Various news organizations have reported numerous incidents of unwanted sexual advances and pay inequity.

In an interview just after the allegations surfaced, Sanders apologized but also noted he was “a little busy running around the country trying to make the case.”

“What they experienced was absolutely unacceptable and certainly not what a progressive campaign — or any campaign — should be about,” Sanders said Jan. 10 on Capitol Hill. “Every woman in this country who goes to work today or tomorrow has the right to make sure that she is working in an environment which is free of harassment, which is safe and is comfortable, and I will do my best to make that happen.”