Hillary Clinton picked up the endorsement of New Hampshire Gov. Maggie Hassan Friday, adding the state's top Democrat to a list of backers that also includes Sen. Jeanne Shaheen, the state chapter of the National Education Association, and a small army of current and former government and party officials.

She's also getting campaign-trail help from two top Democrats that come from rival Bernie Sanders's neighboring home state of Vermont — Gov. Peter Shumlin and former Gov. Howard Dean.

This validation is coming at a time when Sanders leads Clinton in polls in the Granite State: by 4 percentage points in a WBUR survey and by 7 percentage points in one from Monmouth University.

The paradox there — that Democratic officials are swinging in line behind Clinton even as Sanders is showing strength in polling — speaks both to the skill Clinton's demonstrated as an inside political player and the kind of advantage that gives her in a primary race that many pundits insist is closer now than it really is. It's also one of the many factors that could figure in Vice President Joe Biden's decision about whether to jump into the race.

Democratic presidential primary endorsements actually matter a lot

There's room to argue over the exact value of most political endorsements — and there's a good case to be made that the vast majority are pretty meaningless — but presidential primary endorsements, particularly on the Democratic side, can matter a lot.

There are three basic reasons for that:

Members of Congress, governors, and certain other party officials are "superdelegates" to the Democratic National Convention next year, meaning they have a vote in the tally that decides the nomination and that they aren't pledged to vote for a candidate chosen by the voters of their state or district. Elected officials often — though not always — have pretty significant political organizations and fundraising networks. They can help a presidential candidate put together a ground game on their home turf and squeeze every last dollar out of of every last donor. This is particularly true of top statewide elected officials such as governors and US senators.

The policy differences between candidates in a party primary can be pretty small, and some voters may take cues from their favorite local pols to pick a candidate for the nomination. The endorsement of a popular official confers a certain credibility on a candidate.

There's another reason that the spate of endorsements is a big deal for Clinton. She's reducing the number of big-name Democrats available as validators for Biden as he deliberates over a run. That's not going to be the deciding factor for him, but, just as he's looking for fundraisers to fill his coffers, you can be sure he's also keeping tabs on who is still open to lending their name and political operation to him.

Clinton is dominant on Capitol Hill

Sanders has been in Congress for almost a quarter of a century, and Biden's been a senator or president of the Senate (one of his roles as vice president) since 1973. But Clinton, who was only a senator for eight years, has vacuumed up support from House and Senate Democrats.

That's attributable to a potent mix of genuine support, fear of being on the wrong side of a Clinton team with a long memory, and the self-interested belief that Clinton would be more attentive to the care and feeding of lawmakers than Obama has been.

She earned high praise from House Democrats after a private meeting this summer when she drew a subtle but unmistakable stylistic contrast with Obama.

"I want to be your partner in policy and your partner in politics," she told them.

That single line — so anodyne by itself — spoke directly to the frustration Democratic officials feel toward a president they believe has shut them out of his policy-making process, denied them face time, and failed to provide them political cover when they vote with him. Clinton, many of them think, will do better. And even though Biden was Obama's chief emissary to the Hill, there are many Democrats who believe he needlessly negotiated away Democratic priorities in deals with Senate Republican leader Mitch McConnell.

Of the 46 senators who caucus with Democrats, 30 have endorsed Clinton, according to a list kept by The Hill, a newspaper that covers Washington. One of the remaining 16 is Sanders and two are the senators from Biden's home state of Delaware. Even Sanders's fellow Vermonter, Patrick Leahy, has endorsed Clinton.

In the House, 89 of 188 Democrats have endorsed Clinton — and no one has endorsed Sanders or Biden — according to The Hill's list. So, overall, more than half of the Democrats in the House and Senate already have endorsed Clinton.

The ultimate show of loyalty: More than two dozen Democrats have given to Clinton out of their campaign or political action committee accounts, and half a dozen of them — including Sen. Claire McCaskill — have written personal checks to her. Among Clinton loyalists, McCaskill was the most hated of Obama's surrogates in 2008.

The politics of inclusion

While Democratic lawmakers make for a good focus group, they're hardly the whole story. Clinton is assiduously courting key constituencies by including them in the development of her platform, aiming policies directly at them, and building a campaign operation that clearly reflects the full diversity of the Democratic Party.

It's tough to bash Clinton when you're sitting at her table

Clinton's painstakingly built institutional support. Here's her secret: Invite potential adversaries to the table, include some of their ideas in policy, and then send their laudatory remarks out to reporters. This signals to them that she'll be inclusive if she's elected president, and makes it hard for them to criticize her later on.

The MO has been most evident on the economic agenda Clinton rolled out this summer. She consulted more than 200 economists, according to her campaign. Her aides worked closely with officials at the Roosevelt Institute, a progressive think tank, in advance of her official campaign launch rally on Roosevelt Island in New York and before her first big economic speech.

More important, she's taking input from liberal economists who emphasize "fairness" in the economic system and have warred with more Wall Street–oriented Democratic economists such as Bob Rubin and Larry Summers. Rather than choose between their "growth" wing of the Democratic economic establishment and the "fairness" wing, represented by the likes of Joe Stiglitz and Alan Blinder, Clinton has opted for both — and managed to co-opt both.

"Hillary Clinton began to offer the kind of comprehensive approach we need to tackle the enormous economic challenges we face, one that is squarely in line with what we have called for at the Roosevelt Institute," Stiglitz said in a statement when Clinton began rolling out her economic agenda.

That leaves her rivals with few respected economists left to vouch for their ideas, and it speaks to her mastery of coalition politics.

"She knows this is a team sport," said Lea Crusey, the acting executive director of Democrats for Education Reform, who praised Clinton in a post on Medium topped with an '80s-vintage picture of Clinton and the words "Hillary Rodham Clinton: Ed Reformer Since 1983."

Her campaign reflects the Democratic Party and its priorities

When advocacy groups are upset with policy, they often point to a lack of representation within a candidate or president's inner circle. When they want to enhance their representation, they often argue that policy decisions aren't being resolved in their favor. It will be tougher to criticize Clinton because she's covering both bases. The composition of her staff and the composition of her platform reinforce each other.

Clinton has a corner on the top talent in the market for Democratic operatives, including people of color, which has made it more difficult for Sanders, O'Malley and others to staff up. It also limits Biden's options in terms of building a top-notch campaign operation.

Clinton's also done an interesting thing with her top operatives that helps her show the diversity of her staff: She's building their brands. One of the effects of that is to make the face of the campaign more of a mosaic and more representative of the party's constituencies. Another effect is to empower those aides as they court voters and activist groups.

Amanda Renteria, the campaign's political director, was allowed to participate in a Los Angeles Times profile that chronicled her politicking at a National Council of La Raza conference and, separately, with young Latino voters.

Under Renteria's direction, Clinton organizers are showing up in Latino and other minority communities in a variety of ways. Often it's not even to talk much politics. Renteria, 40, recalls a recent networking event at a bar in Philadelphia where the millennials who showed up wanted to discuss career strategies, how to go about paying off student loans and what her family thinks of what she is doing with her life. So they did.

Marlon Marshall, a former Obama White House aide and 2008 Clinton campaign operative, has similarly become a face of the campaign for activists. Marshall, who is black, emceed Clinton's kickoff rally and emails donors to give them updates on what he sees from his perch as the campaign's "director of states."

The diversity in the upper echelons of Clinton's campaign is nothing new. Her campaign managers in 2008 were Patti Solis Doyle, who is Latina, and Maggie Williams, who is black. Her chief of staff at the State Department, Cheryl Mills, is black, and the vice chairwoman of her current campaign, Huma Abedin, is of South Asian descent. Identity politics still matter — perhaps more now than the last time Clinton ran. So the diversity, in and of itself, strengthens the likelihood that Clinton proposals aimed at specific constituencies, like ending the "era of mass incarceration" and protecting more unauthorized immigrants from deportation, will be well-received. Likewise, the policies make it more likely that Clinton's campaign emissaries will be well-received.

Political campaigns are dynamic, and things could change. But Clinton's mastery of the inside game — winning over prominent Democrats, co-opting the party's top policy thinkers and cornering the market on staff — is a factor that will help her as she tries to fend off at least Sanders and possibly Biden. They simply have fewer resources available to them.