(CNN) Nearly two dozen top progressive groups are joining forces ahead of the midterm elections in an effort to boost Democratic turnout in November and parlay a surge of liberal energy into pre-election activism.

The groups, which include MoveOn, Indivisible, Organizing for Action, Latino Victory, United We Dream and the Working Families Party, among others, will launch a new online organizing hub Tuesday called The Last Weekend, with an aim of amassing more than a million volunteer hours during those crucial pre-election days.

"You hear a lot of that messaging: 'Go vote. We all need to vote.' And yes, we all need to vote. But (Democrats are) in these circles where we're talking to a lot of people that agree with us," said Ethan Todras-Whitehill, the executive director of Swing Left, the group spearheading the effort.

"We need a lot more from those people who are activated," he said.

Organizers from participating groups are also hoping the initiative will help streamline their activities, reducing the number of redundant or confusing appeals to potential volunteers.

"What this allows us to do is unify on brand and unify on a message, which is something that the Democratic Party gets dinged for (being bad at) a lot," Todras-Whitehill said.

The size of the coalition is meant to be a message in itself, a signal that the wider effort to coalesce the sprawling political left ahead of the vote, and tamp down on intraparty squabbling, is working.

"The 'Dems in disarray' joke didn't come from nowhere," said Jesse Lehrich, communications director for Organizing for Action. "Key progressive players have too often slipped into prioritizing their own narrow interests to the detriment of achieving the movement's shared goals. But I think this cycle has really been different -- everyone seems to recognize the magnitude of the moment."

Progressive groups are anxious not to squander what many expect to be a wave of Democratic voters desperate to put a check on President Donald Trump's agenda, from the local level to higher-profile House and Senate races. Celebrities like the actress Rashida Jones, who directed a video that will accompany The Last Weekend rollout, have been enlisted to help spread the word. The website, too, is branded with a direct appeal -- and a reminder -- designed to conjure up the excitement associated with the protests of the past two years.

In large print, on a sparse homepage, it reads: "We've marched. We've rallied. Now we're ready to give it everything we've got, on the last weekend before the midterm elections."

With that in mind, visitors will -- with the specifics based in part on which organization they were funneled in by -- then be directed to a specific set of actions. By securing volunteer commitments in the near team, organizers reason, they'll be able to shuffle their resources as Election Day nears and circumstances on the ground shift.

"When folks commit early, they're more likely to volunteer early. They're going to make a plan," MoveOn's Ashley Bryant said. "It's called The Last Weekend, but as we start to get folks on this list, we're going to start educating them about all the ways that they can get involved."