State party chairs have tentatively agreed to vote as a unified bloc for chairman, according to several sources, making their votes critical to any candidate.
And some chairs are considering runs themselves.
"I'm thinking about it. I'm thinking long and hard. I haven't made a decision," said Harrison, the first African-American Chair of the South Carolina Democratic Party and former aide of Rep. Jim Clyburn, the third-ranking Democrat in the House.
"I understand what state parties need. Particularly state parties that aren't in battleground states," Harrison told NBC News. "I would be full time. That would be my job ... I don't want to go back to a sitting member of congress being the chair. As someone who worked and served as state party chair, it is hard to do both well."
New Hampshire Party Chair Ray Buckley, who heads the Association of State Democratic Chairs, has also been fielding supportive calls, according to a source familiar with his thinking. But he has not indicated his interest level in the national chairmanship.
"The entire DNC building needs to be turned upside-down," Buckley said on a conference call with other state party chairs Thursday night, according to a source on the call. "The DNC must move away from a DC-centric image. We need to have the DNC investing in state parties brick and mortar, in our communications team, in our digital presence, so that the people know we are in our local communities and working hard to push back on Donald Trump and what is shaping up to be our worst nightmare: his Cabinet, his Congress, and regretfully his Supreme Court."
Given the immense task ahead for Democrats, some have floated the idea of splitting the chair into two jobs — one more public-facing and one more operational.
Meanwhile, O'Malley, who announced his interest Friday morning, is spending the weekend making calls to some of the several hundred other Democrats who make up the committee, according to a source close to O'Malley.
O'Malley allies believe he can straddle the Clinton-Sanders divide, since he was in neither camp, and argue that he can do both the public aspect of job that Ellison might excel at and the more tactical party-building job that Buckley and Harrison call for, given his work as chairman of the Democratic Governors Association. And they note he'd be a full-time chair.