ATLANTIC CITY, N.J. — Bernie Sanders didn’t endorse Hillary Clinton the day after Barack Obama launched his own "I'm With Her" campaign — actually, he got booed by House Democrats fed up with his slow walk to the finish line — but there were growing signs that an announcement may be in the works.

Clinton’s campaign hastily released a new college affordability plan, offering free college tuition to working families, just hours before the presumptive Democratic nominee was set to excoriate Donald Trump’s business record in the heart of his failed Atlantic City casino empire.


And on Wednesday, Clinton’s campaign in Brooklyn was going back and forth negotiating a potential joint rally with Sanders in New Hampshire next week, a person familiar with the matter told POLITICO. The Vermont senator drubbed her by more than 20 points last February in the neighboring state, marking a soul-searching, low point of Clinton’s campaign.

Clinton wasn't planning to address her big policy shift in this down-on-its-luck casino town, but the announcement was intended as a peace offering to the Vermont senator — and the first major public step towards an endorsement sources close to the negotiations now expect to arrive as soon as next week.

By leaking the plan, Clinton made a significant concession to Sanders on one of the driving issues of his campaign — free public college for all — a pledge that has in part accounted for his stunning 5-to-1 margin over the party's nominee among voters under the age of 30.

Clinton’s new proposal, the product of weeks of negotiations between the campaigns, outlines a plan to provide free college for families earning $125,000 or less at in-state public colleges and universities, which would include about 80 percent of the college-age population.

It also represented something of a U-turn from her rhetoric during the hotly-contested primary she is hoping to end, once and for all, before the Republicans convene in Cleveland later this month.

“My late father said, ‘Anytime someone tells you it’s free, read the fine print,’” Clinton said during a rally ahead of the June 7 California primary, mocking Sanders’ plan as a pie-in-the-sky promise with no funding details to back it up.

“It doesn’t add up, my friends,” she claimed at an April campaign stop in Wisconsin. Her college plan, in contrast, had allowed students to refinance their student loans to ease the burden of debt.

Clinton didn’t mention the shift on debt-free college at a scorching outdoor rally on the Atlantic City boardwalk Wednesday -- she didn’t take the gas off of bash-Trump day. In attacking the former casino magnate, she played the uncharacteristic role of a street politician embroiled in a local city council race -- trolling Trump by pitching her podium in front of his abandoned waterfront casino, the faded outline of his name all that was left of his once-glitzy palace of populist sin.

“You can just make out the word Trump where it used to be written in flashy lights,” Clinton said. “He had the letters taken down a few years ago...Isn’t he supposed to be some kind of amazing business man? What in the world happened here?”

Many Clinton supporters have been asking the same questions of Sanders, and he was lustily booed by Clinton backers in the House on Wednesday when he met with them behind closed doors in what was supposed to be a polite chat about the future of his movement. Sanders, for his part, has vacillated between public admissions his campaign failed and statements of defiance, challenging Clinton's Wall Street connections and suggesting the process of nominating her was, at times, rigged and undemocratic.

But her college plan was enough to appease the truculent Vermont independent-turned-Democrat, for the day at least — and hinted at a larger agreement. In a statement coordinated with the Clinton campaign, a Sanders spokesman said he welcomed the proposal that “combines the best features of plans that she and Sanders brought forth during the campaign.”

The Sanders campaign did not respond to requests for further comment.

The college plan designed to bring Sanders and his supporters along was part of a time-consuming end game weeks in the making.

Over the past few weeks talks between Clinton campaign manager Robby Mook and his Sanders counterpart, Jeff Weaver, have lurched along without, until now, producing a clear result. The issue wasn't ideology, necessarily, and the two operatives have developed a decent working relationship. In addition to the concessions on free college, Clinton and her team, according to two people briefed on the talks, have been willing to discuss further strengthening rules on Wall Street banks — though she remains opposed to the re-institution of the lapsed Glass-Steagall separation between vanilla banking and high-risk securities investment.

The two sides had bogged down of the specific details of policy — not surprisingly, Sanders has insisted on the biggest possible proposals while Clinton's bean-counting policy team has focused on the details of funding, legislation and implementation.

The college plan announced Wednesday was designed to steer clear of the cost implementation concerns, by capping the free college at $125,000 so that, as Clinton likes to point out on the campaign trail, Donald Trump’s kids still don’t qualify for any federal support.

But, in general, sources from both sides said the talks have been more focused on getting Sanders and his wife, Jane, acclimated to the idea that his revolution came up short — and it's time for him to play a supporting role in the fight against Trump.

Since Clinton’s victory speech in New York when she clinched the nomination on June 7, her aides have consistently said they believe Sanders should be part of the convention and that they were open to “celebrating what he has accomplished.”

Clinton's brain trust, top Democrats told POLITICO, have been torn between the need for patience — and growing sense of annoyance that Sanders has bungled the tradecraft of his withdrawal, losing leverage as more Bernie supporters jump to the Clinton camp, a conclusion supported by recent polls.

Nor has the Brooklyn brass waited for Sanders and his team to come on board before reaching out to his supporters in the states: Over the past two weeks top Clinton aides, including campaign manager Robby Mook, quietly convened town halls with Sanders volunteers and staff in battleground states — a listening tour in which they have absorbed the frustration and skepticism that fueled the Vermont senator's insurgency in the first place.

“We admire and have a lot of respect for what Senator Sanders and his campaign has achieved,” Mook told POLITICO last month. “Our campaign, and Senator Sanders and his campaign, are mutually committed to ensuring that Donald Trump does not get into the Oval Office. This isn’t simple and won’t happen overnight, but the work is well underway.”

In typical Sanders fashion, he was still holding out even as the wheels of unification were churning toward the inevitable final result. Asked Wednesday morning about any plans to endorse Clinton, Sanders said there were still policy initiatives on the table that needed to be worked out.

One hurdle that remains — the draft of the platform slated for final approval before the full Platform Committee this weekend at a meeting in Orlando.

“The goal isn't to win elections,” Sanders said at one point during his testy meeting with Democratic lawmakers on the Hill Wednesday, according to multiple lawmakers and aides in the room. “The goal is to transform America.”

Glenn Thrush contributed to this report.