Elizabeth Warren’s all-but-announced candidacy for the Massachusetts US Senate seat once held by Edward Kennedy is a state-based campaign. But it has national implications.

It’s not just that a Warren candidacy could provide Democrats with a needed pick-up of a currently Republican-held seat — although that’s a big deal for the party, which faces a dismal electoral map in 2012. If the Harvard Law School professor who became the chief advocate for real banking reform and the development of a federal Consumer Financial Protection Bureau runs and defeats Scott Brown, R-Massachusetts, she will instantly become an essential spokesperson for progressive values in national economic, regulatory and fiscal policy debates.

Put Warren next to stalwarts like Oregon Democrat Jeff Merkley, Minnesota Democrat Al Franken, Iowa Democrat Tom Harkin, California Democrat Barbara Boxer, a reelected Vermont Independent Bernie Sanders, a re-elected Ohio Democrat Sherrod Brown, as well as progressive newcomers like Wisconsin Democrat Tammy Baldwin and Hawaiian Democrat Mazie Hirono, both expected candidates open Senate seats, and you’ve got the makings of what Paul Wellstone always wanted: a Senate Progressive Caucus.

The calculus extends even further with Warren, however. Her ability to grab the spotlight and use it to push the discourse to the left on economic issues that the media so frequently neglects makes the prospect of her candidacy and Senate service potentially transformative for movements and a party that will — no matter what the 2012 presidential election result — begin pondering sometime next year the challenge of identifying leaders of the post-Obama era.

The Warren calculus has not been lost of progressives and progressive groups that have indicated a clear intention to help Warren — whose criticisms of Wall Street will require her to raise money from the grassroots — mount a winning campaign.

The Progressive Change Campaign Committee has been promoting a Warren candidacy for weeks, and just announced that it will deliever a check for more than $105,000 to Warren’s exploratory campaign.

Emily’s List is up with a new “Tell Elizabeth Warren: We’ve Got Your Back!” campaign.

Of particular importance is the decision of National Nurses United, a union that has made the shifting of the debate central to its 2012 political work, to take the unusual step of endorsing Warren before the professor formally announces her candidacy.

Technically, the 170,000-member union is endorsing Warren’s exploratory candidacy. But the move by the NNU left no doubt about the union’s sentiments. And it sends a powerful signal as regards the Senate race, as the endorsement by the national union follows a recommendation from its affiliate, the 23,000-member Massachusetts Nurses Association, which has also endorsed Warren.

“Even though she is not yet an official candidate, the MNA Board has taken the unprecedented step of voting to support her,” said MNA President Donna Kelly-Williams, RN. “Her dedication to the nation’s middle class, which she has demonstrated through her work as a faithful consumer advocate both locally and nationally, reflects one of the MNA’s key goals: Restoring a basic standard of living for working people by creating financial remedies that hold Wall Street accountable while protecting those who live and work on Main Street USA.”

The Massachusetts Nurses Association maintains one of the most focused and effective political operations in the state, and it is especially strong in western Massachusetts where Warren will need grassroots support to secure the Democratic nomination and election in November. In Massachusetts and other states, NNU works closely with Progressive Democrats of America, the activist group that has been in the forefront of fighting to push the Democratic Party toward a more militant stance when it comes to taxing the rich and defending Social Security, Medicare and Medicaid.

Warren will also benefit from NNU’s strong national political operation, which NNU executive director RoseAnn DeMoro, said would focus particular attention on the Massachusetts campaign.

“Nurses have aligned with the public in seminal battles over the future of our communities throughout the country,” said DeMoro. “Nurses and patients together have shown the creativity and commitment to winning such efforts. We can take back our country from Wall Street. Elizabeth Warren will be a great ally.”