BOSTON — Hillary Clinton and Bernie Sanders are battling it out in Massachusetts ahead of the March 1 primary here — and the state’s most important endorsement, Sen. Elizabeth Warren, is still sitting on the sidelines of the debate, watching and waiting for her moment of maximum leverage.

Even as Clinton turns Massachusetts — a predominantly white, progressive New England state that should be tailor-made for Sanders — into a battleground Super Tuesday state, the campaign has been quietly respectful of Warren’s desire to remain neutral.


In part, that’s because the progressive standard-bearer — and the only member of the state’s congressional delegation who has not endorsed Clinton — is expected to play the role of peacemaker in the Democratic Party at some point in the months leading up to the convention, sources familiar with Warren’s thinking said.

If Clinton wins enough delegates by the end of March to become the presumptive Democratic nominee, Warren is expected to negotiate hard before giving her support to Clinton. In doing so, she could play a critical role helping to bring young, enthusiastic Sanders supporters into her fold.

Warren’s endorsement has grown in importance for Clinton over the past 10 months, as Sanders transformed before the Democratic front-runner's eyes from a little-known senator from a small state into a serious presidential contender energizing millennial voters across the country with his message of economic inequality.

The Clinton campaign has tried to give Warren the space she wants to make her decision on an endorsement, while at the same time elevating her top issues of Wall Street regulation, college debt and tax fairness. Clinton’s ability to gain Warren’s endorsement any time soon, sources said, depends on whether Clinton is able to establish enough of a delegate lead over the next month to make it virtually impossible for Sanders to clinch the nomination.

But even in that case, Warren has no firm timetable for making a decision, said a source familiar with her thinking.

As it waits for Warren, the Clinton campaign has remained in constant contact with her office and her allies. Clinton’s policy team in Brooklyn has assiduously courted financial reformers in Warren’s circles, like former Consumer Financial Protection Bureau official Rohit Chopra, while it has crafted its proposals on student loan reform and Wall Street regulation. Clinton's policy team in Brooklyn often turns to Warren's shop for consultation on regulatory issues.

There are other, more direct, chains of communication as well. Campaign CFO and former top federal financial regulator Gary Gensler is a close Warren ally. And longtime Clinton consultant Mandy Grunwald remains an important go-between — Grunwald worked a Warren’s top paid media consultant for her 2012 Senate campaign and is a longtime adviser to both politicians.

On Monday, Clinton made two stops in Massachusetts — in Springfield and in Boston — a significant investment of the candidate’s time the day before Super Tuesday, when 11 states across the country will cast their ballots.

There, she was already previewing a general election message targeting Donald Trump. “I don’t think America ever stopped being great,” she said. “What we need to do now is make America whole. Sanders also held a Massachusetts rally, in Milton, on Monday night.

But at least in Massachusetts, the primary battle is still going full steam. A victory here would be symbolically important for Clinton — after a landslide 48-point victory in South Carolina, it would demonstrate there is little room for Sanders if she is able to win both African-American voters in the South and progressive white New Englanders who should be the Vermont Senator’s bread and butter.

Clinton’s campaign decided to play hard in Massachusetts after the crushing 22-point loss in New Hampshire that rattled both Hillary and Bill Clinton and caused them to question their own campaign strategy.

Veteran Boston-based political operative Charlie Baker, who serves as the campaign’s chief administrative officer, took a break from his work from Brooklyn headquarters to organize the state. “After New Hampshire, we decided I should stay here,” Baker, who served as a senior adviser to John Kerry’s 2004 presidential campaign, told POLITICO. “I’ve been doing campaigns here since the 1970s.”

Public polls in recent days have shown Clinton leading by 5 to 8 points. “There’s a great base of support here,” Baker said. “We’re pleasantly surprised — Vermont is on the border.”

Clinton has a better shot of winning Massachusetts than she did in New Hampshire, Baker said, because more Democrats than independents vote in the primary. The population of independents is also slightly more educated and older — making them more likely to be in Clinton’s camp.

“It matters because it’s a historically progressive state — my first election, Massachusetts and Washington, D.C. voted for George McGovern,” said Baker of 1972. “I would challenge anyone to find a more progressive place.”

The Clinton campaign now has five paid staffers on the ground here, and seven campaign offices. Baker said 984 volunteers worked for Clinton over the weekend, and the campaign logged 130,000 calls. The campaign has also invested in television ads in the Boston and Springfield markets that include an emotional gun-control-focused spot starring former Arizona Rep. Gabby Giffords.

“We’re doing well among Democrats, and we’re doing better among independents than we did in New Hampshire,” Baker said. “These elected officials in Massachusetts actually do real campaign work. Every single one of these people has actually canvassed, twice, three times.”

Still, Sanders’ team has been focused on Massachusetts — a state where he remains strong in the west and the Boston suburbs, according to local Democrats — even longer. His campaign has long recognized it as an important pickup opportunity to kick off March. His local team, led by former union official Paul Feeney, has five offices in the state and has brought in hundreds of volunteers from its successful New Hampshire campaign.

“I’ve been reminding our staff in state, our volunteers, our supporters to try not to ride the poll-er-coaster,” Feeney said. “When I came on in November, the polling had us down 25 points.” Feeney said the campaign has been building a hyper-local organization, spearheaded by more than 200 town captains, since Jan. 1.

“We knew that the entire congressional delegation and the electeds would be against us,” Feeney said. “We built an organization, we didn’t borrow one.”

Sanders has also been courting Warren by praising her on the trail as he campaigns across her state. “What our campaign has been talking about is … that we have a rigged economy, something that your Sen. Elizabeth Warren has talked about,” Sanders said at a rally in Amherst last week. “Thank you all for sending Elizabeth to the Senate.”

Even so, Sanders’ staffers who were once confident that Massachusetts would be one of the five winnable states on Super Tuesday — along with Oklahoma, Minnesota, Vermont and Colorado — now think it will be a neck-and-neck race and are growing increasingly nervous about Clinton’s scaled-up operation.

Sanders’ campaign used its months of New Hampshire advertising in the Boston media market as a way to build up his presence in Massachusetts, according to senior aides. That makes the stakes even higher.

“If she wins in Massachusetts it’s likely to be a long night for Bernie Sanders,” explained Steve Koczela, president of the MassINC polling group, alluding to the pair of recent polls — including his own — that show Clinton with an unexpected lead here. “This forces the Sanders campaign to play a bit of defense in a state where they were hoping to win by quite a bit."