Amid general disgust among progressives, the activist group MoveOn.org on Friday announced it would launch a "donor strike" against the Democratic Party over Sen. Chuck Schumer's (D-N.Y.) break with colleagues and President Barack Obama over the Iran nuclear agreement, calling Schumer's opposition of the deal "outrageous and unacceptable."

Schumer, who is angling to take over as Senate Minority Leader following the scheduled retirement of Harry Reid next year, announced late Thursday that he would vote against the deal.

"I believe Iran will not change, and under this agreement it will be able to achieve its dual goals of eliminating sanctions while ultimately retaining its nuclear and non-nuclear power," he said.

MoveOn said Schumer's reasoning—which aligns with that of "Republican partisans and neoconservative ideologues"—is an attempt to "put the nation on a path to war" and must be met with decisive action. The organization, which raises funds for candidates it identifies as progressive, launched both a donor strike against lawmakers who oppose the deal and a call for Democrats in Congress to "find a new leader."

The group's political action executive director Ilya Sheyman released an impassioned statement on Friday announcing the boycott, which will "organize grassroots progressives across the country to withhold campaign contributions from the Democratic Senatorial Campaign Committee and from any Democratic candidate who succeeds in undermining the president's diplomacy with Iran."

"No real Democratic leader does this," Sheyman said. "If this is what counts as 'leadership' among Democrats in the Senate, Senate Democrats should be prepared to find a new leader or few followers."

The strike urges MoveOn's collective 8 million members to withhold $10 million in campaign contributions within 72 hours of Schumer's announcement.

Lawmakers have until mid-September to vote on the agreement. Obama needs 34 votes to sustain a veto of any legislation opposing the deal. A Schumer aide told CNN on Friday that the senator would also act to override that veto.

As one of the most powerful and staunchly pro-Israel Democrats in the Senate, Schumer's stance on the deal has been highly anticipated since it was announced in July after years of negotiations between Iran and world powers, including the U.S., Russia, China, the United Kingdom, France, Germany, and the European Union. If passed, the deal will lift sanctions on Iran in exchange for limits to its domestic nuclear program.

Both the Israeli government and AIPAC, the dominant pro-Israel lobbying group on Capitol Hill, have come out strongly against signing any agreement with Iran. The swift and heated response to Schumer's decision demonstrates both the significance of his vote and the stakes of the agreement.

"Risking American lives in wars of choice isn't leadership, it's small and backward," Sheyman said on Friday. "Frankly, we thought Senator Schumer and other Democrats in Washington had learned their lesson after being misled into supporting a misguided war of choice in Iraq."

Becky Bond, the political director of CREDO Action, told The Hill on Friday, "Chuck Schumer was wrong on Iraq and he is wrong on Iran. Schumer's decision to join Republicans in attempting to sabotage the Iran nuclear deal once again shows that he is unfit to lead senate Democrats...perhaps it is time to change his nickname from Wall Street Chuck to Warmonger Chuck."

Bond's suggestion echoed on Twitter under the hashtag #WarmongerChuck:

#warmongerchuck Tweets