(CN) — Former Vice President Joe Biden announced his presidential bid Thursday in a video posted to Twitter, warning that the re-election of President Donald Trump will put American values and “our very democracy” at stake.

Showing clips from the 2017 white nationalist protest in Charlottesville, Va., where one counter protester lost her life, Biden’s video expresses discomfort with the words President Donald Trump used to respond used to respond to the event.

“Very fine people on both sides? With those words, the president assigned a moral equivalent between those spreading hate and those with the courage to stand against it,” Biden tells the camera. “In that moment, I knew the threat to this nation was unlike any I had ever seen in my lifetime.”
He further pressed that we needed to return to an America where “everyone is treated with dignity and gives hate no safe harbor.”

“I believe history will look back on four years of this president, and all he embraces, as an abhorrent moment in time, but if we give Donald Trump eight years in the white house he will forever and fundamentally alter the character of this nation,” Biden said.

This is Biden’s third run at the presidency. For months now Biden, 76, has been teasing the public about entering the race, accidentally touting his “progressive running record” before a crowd at the Delaware Democratic Party dinner in March and telling a conference of firefighters chanting his name to save their support “a little longer.”

Even foreign leaders were said to be egging him on to run at the Munich Security Conference in February, saying the country could benefit from his strong foreign-policy background.

On March 20, reports surfaced that Biden was scouting for donors who could help him raise more than $6.1 million his first day, an amount that would put him ahead of Beto O’Rourke, who holds the record for first-day campaign donations among Democratic primary candidates.

Among a diverse array of contenders from the left, which includes a number women, several people of color and a gay man, Biden has been leading the polls even before he announced his candidacy.

In a March 19 national poll of 487 respondents conducted by Emerson College, Biden and Senator Bernie Sanders both garnered 26 percent of participants’ support. Biden led among voters from 50 to 64 years old who supported Hillary Clinton in the 2016 primaries. Biden was the only candidate to poll more than 10 points ahead of President Donald Trump, with 55 percent of those polled to Trump’s 45 percent.

The former president was still enjoying strong numbers on the eve of his announcement: Pollsters at Morning Consult/Politico reported Wednesday that Biden led Trump by 8 percentage points in a hypothetical 2020 general election matchup.

Advocates of Biden, who was first elected to the U.S. Senate in 1972, say he could pull votes from a working- and middle-class white base, African Americans because of his affiliation with President Barack Obama, and the LGBT community for his support of gay marriage. He had a reputation for championing the middle class while he was in the Senate and White House, playing a part in establishing policies that capped student loan payments and improved retirement security.

Because he is, like Trump, an older white man, some Democrats see him as a sturdy candidate, who could bounce back from Trump’s expected criticism on the campaign trail and steal swing votes from Republicans who couldn’t bring themselves to vote for Clinton in 2016.

Just weeks before announcing, however, Biden’s reputation came under scrutiny when Lucy Flores, a former Democratic nominee for Nevada lieutenant governor, claimed that he had kissed the back of her head and touched her shoulders inappropriately in before speaking at her campaign event in 2014. Other women have made similar claims of inappropriate touching, too, and Biden has since vowed to be “more mindful” of this conduct.

Even discounting these allegations, skeptics have expressed doubt that Biden could pull votes from progressive Democrats. They cite Biden’s vote to expand mass incarceration through the 1994 Violent Crime Control Act, and his vote to authorize U.S. use of military force in Iraq under President George W. Bush.

As a senator, Biden presided over the 1991 confirmation hearings of Supreme Court Justice Clarence Thomas and declined to take Anita Hill’s sexual harassment complaints seriously. He also has been criticized for his opposition to school busing in 1975 as a palliative for racial desegregation. Biden at the time called busing “a rejection of the entire black awareness concept, where black is beautiful, black culture should be studied; and the cultural awareness of the importance of their own identity, their own individuality.”

Biden’s reputation as a middle-class advocate has also come under scrutiny from the left, many of whom feel that “Uncle Joe” may be farther out of touch with his voting base than he’d like to acknowledge. Politico has reported that he charges more than $100,000 for speaking appearances, owns a $2.7 million vacation house, and that his latest book deal is estimated to have pulled in seven figures.

Critics have said that as an old-school, white, male politician, Biden will struggle to connect with younger Democratic voters. Electing Bernie Sanders, a self-described democratic socialist, would break new ground, as it would give the United States its first Jewish president.

And the party’s women may be looking for a female candidate who would represent them in the battle for gender equality, in line with the #metoo movement, and call attention to the country’s problems with sexism and sexual assault.

With Biden leading the ticket, Democrats would have to work hard to prove to younger voters, African-Americans and Latinos that his campaign offers something fundamentally different.