PORTSMOUTH, N.H. _ Democrats took a long-anticipated step toward unity Tuesday as Sen. Bernie Sanders endorsed Hillary Clinton, praising the party platform and its presumptive nominee here in the state that gave him his most powerful primary victory.
"This campaign is about the needs of the American people and addressing the very serious crises that we face. And there is no doubt in my mind that, as we head into November, Hillary Clinton is far and away the best candidate to do that," Sanders said to the cheers of hundreds of partisans crowded into a high school gymnasium here, Clinton nodding at his side.
Although long-awaited and, to some extent, anticlimactic, the rally was nonetheless a positive moment for the Clinton campaign, which has spent considerable time over the last week grappling with the aftermath of FBI Director James B. Comey's tough condemnation of how she handled classified email while secretary of state.
The joint appearance here, in the state whose primary did more than any other to propel Sanders into the role of a true threat to Clinton, came after weeks of negotiations and careful choreography.
Sanders moved cautiously in Clinton's direction � too slowly in the eyes of some Democrats � as her campaign edged toward his positions on major issues, most notably proposals to increase federal help with the cost of going to college and expanded efforts to cut the cost of health care.
"It's fair to say that the Clinton campaign and I, our campaign, are coming closer and closer together," Sanders told reporters Saturday after Clinton unveiled her updated health care plan.
The proposal included a $40 billion increase in money for community health centers, a priority for Sanders, and a renewed call for the sort of "public option" insurance plan for which President Barack Obama failed to secure when Congress passed the Affordable Care Act in 2010.
As his language Saturday indicated, Sanders has doled out his praise for Clinton in small helpings in the weeks since she in effect clinched the Democratic nomination. How effusive he was in Tuesday's rally was being carefully watched, not least by his die-hard supporters, some of whom even Monday night were insisting on social media that the joint appearance might not constitute a true endorsement.
And the future beyond the rally remains unclear. Neither side has said how actively Sanders will campaign on Clinton's behalf in the months until the November election.
During the final stages of the primaries, after her victory began to once again seem inevitable, Clinton talked repeatedly about the intense campaigning she did on Obama's behalf after he defeated her in 2008.
Sanders has said he will do "everything I can" to defeat Trump, but before Tuesday had not specified what that means.
By now, polls show that most Sanders supporters already have made their peace with voting for Clinton � spurred on by the prospect of Trump, the presumptive Republican nominee.
Clinton already gained a high-energy endorsement from Sen. Elizabeth Warren of Massachusetts, whose nationwide base of support overlaps with Sanders'. Clinton also has campaigned publicly with Obama and plans to do so soon with Vice President Joe Biden.
Polls have indicated that Democrats are more unified than they were at this point in 2008. That relative party unity is a big part of the reason Clinton has held a consistent lead over Trump of about 4 to 6 percentage points in polling averages since the start of June.
But a significant minority of Sanders voters have resisted calls to fall into line behind Clinton, some feeling that her policies are not far enough to the left to suit them, others opposed to her personally.
Disaffected Sanders voters, especially men, provide a notable chunk of support for the Libertarian nominee, former New Mexico Gov. Gary Johnson.
If a Sanders endorsement brings more of those voters over to Clinton's side, her lead over Trump could be expected to grow by another percentage point or two nationally � enough potentially to swing some close-fought states in her direction.
In part to engineer that outcome, the two sides spent considerable time over the last several weeks negotiating steps toward unity. Clinton's campaign manager, Robby Mook, and his counterpart from the Sanders camp, Jeff Weaver, took the lead, said a Clinton campaign aide, speaking on condition of anonymity to talk about the private negotiations.
The two met for nearly two hours in early June after Clinton and Sanders got together at a downtown Washington hotel. They followed up with a dinner in Vermont � a burger for Weaver and salad for Mook � and have been in near daily contact by email and text messages, the campaign aide said, noting that Sanders' wife, Jane, also played a major role in negotiations.
From early on in the discussions, it was clear that Sanders was focused mainly on specific issues that he could influence Clinton on and that Clinton was willing to accommodate him on at least some of those.
That contrasts with some previous elections in which defeated candidates needed help retiring large debts or wanted jobs for supporters. The Clinton campaign has, however, begun hiring some key Sanders operatives, including a new director of on-campus political organizing.
The two biggest steps came over the last week, with Clinton's expanded plan for college tuition aid and her updated health care plan. Those two apparently met the test that Sanders had set, that Clinton should run on the "most progressive platform" that the Democrats have ever embraced.
Over the weekend, the Democratic platform committee finished drafting the party's positions for this election. Sanders' top aide at the committee said his side had gotten 80 percent of what it wanted.
