Morehouse College student Keron Campbell snaps a selfie with presidential hopeful Pete Buttigieg, Mayor of South Bend, Ind., at Morehouse College on Monday, Nov. 18, 2019, in Atlanta. (Curtis Compton/Atlanta Journal-Constitution via AP)

WASHINGTON (AP) — New uncertainty hangs over the Democratic presidential primary as 10 candidates meet on the debate stage once again.

No longer is there a clear front-runner. The fight for African American voters is raging. And there are growing concerns that impeachment may become a distraction from the primary. Those issues and more will play out tonight when the Democratic Party’s top 10 face off in Atlanta just 75 days before primary voting begins.

Turbulent polling across the early voting states has created a murky picture of the top tier of the 2020 class. As much as Joe Biden is still a front-runner, so are Elizabeth Warren, Pete Buttigieg and Bernie Sanders. The question is who gets the front-runner treatment in today’s debate. Warren was under near-constant attack last month as a new leader. Will Warren continue to face the heat, or will the ascendant Buttigieg or weakening Biden take more hits?

Former President Barack Obama, the most popular Democrat in America, inserted himself into the 2020 primary in recent days by warning candidates against moving too far to the left. His comments create a challenge for Warren and Sanders and an opening for moderates Buttigieg, Biden and Amy Klobuchar to attack. At the same time,

Obama’s involvement offers a powerful reminder of the massive role African Americans will play in the presidential nomination process. It appears all candidates not named Biden have serious work to do when it comes to winning over the black vote. Race and Obama’s legacy could play a major role in shaping the action.