A protester holds up a "Dump Trump" sign in the middle of a campaign rally in Portland, Maine, earlier this month. (Joel Page/Reuters)

Leaders of nearly two dozen progressive groups issued a call to action Tuesday to combat what they described as the "racism, sexism, misogyny, and xenophobia" of Donald Trump's campaign.

"This is a five-alarm fire for our democracy. A hate-peddling bigot who openly incites violence is the likely presidential nominee of one of our nation’s two major parties. It is alarming and dangerous," begins the letter, posted on Medium, the young, social media-oriented publishing platform.

The letter's signatories include the leaders of 20 of the nation's largest and best-known liberal groups, including MoveOn.org, Sierra Club, National LGBTQ Task Force Action Fund, United We Dream Action, NARAL Pro-Choice America, Greenpeace USA, Demos Action and the Service Employees International Union.

In the letter, the group strikes an unusually urgent tone, even for organizations with a political mission.

"Please, join this call to action as though our democracy and our lives depend on it," they conclude. "They do."

The progressive leaders describe Trump's candidacy as a threat to America driven by a strategy rooted in "demagoguery."

"Racism, sexism, misogyny, and xenophobia are the currency of Donald Trump’s campaign. Perhaps most troubling, Trump has repeatedly incited and praised violence against those whom he belittles and with whom he disagrees," they write.

The Trump campaign did not immediately respond to a request for comment.

The progressive leaders invite their counterparts at other organizations to add their signatures to the list and encourage supporters to non-violently mobilize and organize against Trump and his message by holding rallies, having conversations, writing letters to the editor, posting on social media and hosting prayer vigils.

They also encourage supporters to demand elected officials and media outlets condemn Trump.

"Decades of dog-whistle politics from political, corporate, and media elites rigging institutions and the economy in their favor at most people’s expense have fertilized the ground that Trump is now tilling for his own gain," they write.

And, of course, they urge supporters to vote.

"If we stand together in this moment across movements and build together we will not only stop Trump, but continue to create a country that protects and respects the dignity and humanity of all people and allows us all to prosper and thrive," they conclude.

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