Cornel West, the progressive activist and professor, announced a presidential campaign on Monday with the People’s Party, a third party led by a former campaign staff member for Senator Bernie Sanders.

“I enter in the quest for truth, I enter in the quest for justice, and the presidency is just one vehicle to pursue that truth and justice — what I’ve been trying to do all of my life,” Dr. West said in a campaign video posted on Twitter.

In the video, Dr. West said he had decided to run as a third-party candidate because “neither political party wants to tell the truth about Wall Street, about Ukraine, about the Pentagon, about Big Tech.” He called former President Donald J. Trump, the front-runner for the Republican nomination, a “neo-fascist,” and President Biden a “milquetoast neoliberal.”

Dr. West has taught at Yale, Princeton and Harvard and is currently a professor of philosophy at Union Theological Seminary. He is known for his progressive activism, including his sharp criticism of former President Barack Obama.

His campaign video emphasized a list of issues, including wages, affordable housing, abortion rights, universal health care, climate change and “the destruction of American democracy.”

The People’s Party was founded by Nick Brana, who worked on Mr. Sanders’s campaign for the Democratic presidential nomination in 2016, but later broke away. The party tried to recruit Mr. Sanders after his 2016 campaign, but he declined to get involved and again sought the Democratic nomination in 2020.

“Do we have what it takes? We shall see. But some of us are going to go down fighting,” Dr. West said in his announcement video, leaning into the camera and exaggeratedly enunciating the syllables of “fighting.” “Go down swinging with style and a smile.”