Sanders has been pulling Clinton to the left throughout the campaign, on everything from trade to the environment. The crafting of the platform offers a rare chance to enshrine many of those changes and Sanders and his supporters are ready for battle.
Sanders won a key concession from the Democratic National Committee last month securing five seats on the 15-member panel writing the platform (Clinton won six seats and DNC Chairwoman Debbie Wasserman Schultz picked four members.)
One of the first steps will come Wednesday and Thursday when the DNC's platform-drafting committee meets in Washington to hear testimony on possible changes.
America's relationship with Israel is likely to be the nastiest fight in Philadelphia. The starkest indication that Clinton and Sanders were on two separate worlds when it comes to Israel came at the American Israel Public Affairs Committee's annual conference in March -- Clinton delivered a fairly mainline argument in support of Israel as a cherished partner in the Middle East. But Sanders, the only Jewish candidate in the field, delivered a broadside from the other side of the country -- skipping the conference and blasting Prime Minister Benjamin Netanyahu.
"To my mind, as friends, we are obligated to speak the truth as we see it. This is what real friendship demands, especially in difficult times," Sanders said.
Driving home that point will be two of Sanders' five selections for the group which is drafting the platform -- James Zogby, president of the Arab American Institute, once compared Israel's treatment of Palestinians to the Holocaust and Cornel West, a prominent surrogate for Sanders throughout the campaign, once blasted Netanyahu as a "war criminal" in a 2014 rally
(later in the speech he also called Obama a "war criminal" for using drone strikes).
Zogby defended his role in a rare blog post Monday
, after he said he heard two men at a restaurant blasting his involvement in writing the platform.
"In addition to all of the other critical issues Bernie Sanders has raised, he has done our nation and the cause of peace a service by bringing the matter of Israel/Palestine into the national debate. It belongs there and deserves to be discussed on its merits, without rancor and without fear," Zogby wrote.
Sanders has drawn sharp distinctions between himself and Clinton on fracking -- hydraulic fracturing to reach oil and gas deposits -- throughout the campaign, and especially in his run in California.
He then said the party itself needs to take a clear stance against the practice.
"I hope that the Democratic Party platform decides it is on the side of the American people, and I would hope that the Democratic party makes it clear that it has the guts to stand up the fossil fuel industry. That's exactly what I expect in the Democratic National Convention, to do what the American people want," Sanders said last week.
Sanders blasted Clinton in April, accusing her of flatly supporting the controversial practice.
Clinton supported fracking during her time at the State Department, but has taken a more nuanced approach as a candidate.
Keystone XL Pipeline
Count this as a battle Sanders has already largely won, hammering away at the Keystone XL pipeline until Clinton, fairly early in the race, announced her clear opposition to it as wel
l -- after avoiding taking a position on it.
Representing Sanders will be the leader of the fight against the Keystone XL pipeline, Bill McKibben, and representing Clinton will be former Environmental Protection Agency Carol Browner -- who fought ardently for carbon dioxide limits as the leader of Obama's environmental efforts.
Sanders has also pulled Clinton to the left on trade, spurring her to oppose the Trans-Pacific Partnership. The platform approved at the 2012 convention calls for "free and fair trade" -- with a focus on spurring exports while maintaining human rights, environmental and other protections. The key question will be whether the party drops the "free" from its platform.
In one of the most awkward positions of an incredible campaign season, Sanders and Clinton now stand to the left of Obama on trade, eight years after his campaign was given the reins of the platform as the party's presumptive nominee.
Like most battles, on trade, the party has to decide how big its tent will be.
Party leaders and delegates have to strike a balance between saying something clear and bold and leaving enough space for the vast majority of Democrats to support, said Christine Pelosi, daughter of House Democratic Leader Nancy Pelosi and a veteran of party platform battles in California and at the DNC.
Each side, she said, should send in their strongest voice with the hopes that their position is adopted and not start from a point of concessions.
"The warriors have the best diplomatic skills because they know what it is to fight, therefore they can be trusted to go back to their people and say 'I gave it our all,'" said Pelosi, who also runs trainings for liberal and Democratic activists. "If you can get them to agree, you can get everyone else to agree. Both sides will say 'We all had the strongest voice at the table.'"
But, she said, at the end, they have to agree on a statement that will be actually written into the platform -- because otherwise the fight wasn't worth it: "There's no point in having a platform fight if, in the end, people are going to just walk away from it."
Sanders wants Depression-era banking regulations, the Glass-Steagall Act, reinstated and Clinton argues that reinstating old rules ignores the complexities of modern finance.
Wall Street has been a glaring weakness for Clinton throughout the campaign as Sanders has blasted her for giving high-dollar speeches to Goldman Sachs and she stumbled in an early debate, citing the September 11, 2001, terrorist attacks for her support of Wall Street.
Both candidates support keeping a tight rein on Wall Street -- but Sanders and his supporters have been much starker in their language. Like many of the battles, this one is not a question of "Where does the party go?" but instead, "How far?"
Mo Elleithee, former communications director for the DNC, said most of the fights were already hashed out during the primary and any difference is more a matter of how far to the left does the party shift, versus any dramatic changes.
"On most of the economic, bread-and-butter issue I think it's a matter of degrees, not a matter of direction," said Elleithee, who now runs the Georgetown Institute of Politics and Public Service. "Both candidates and the party as a whole wants to raise the minimum wage. Bodth candidates and the party as a whole believes in Wall Street regulation."
Sanders already successfully pulled Clinton to the left on minimum wage -- pushing her from supporting a $12-an-hour minimum to the $15 minimum. The party itself has already adopted the $15 minimum, following a successful push by liberal activists at a DNC meeting last year
. And Rep. Keith Ellison, one of Sanders' picks for the platform panel, drafted legislation that would set the federal minimum wage at $15 an hour.
Protesters being organized by Good Jobs Nation plan to show up to the platform drafting hearing in Washington Wednesday to ensure the $15 stays in the platform.
Platforms are typically dominated by the presumptive nominee -- the candidate who had long ago locked up the nomination and was the effective leader of the party heading into the convention. And planks inside the platform have often been reserved as consolation prizes for the runner-up.
Universal health care was a consolation prize Clinton won from Obama in 2008, with his promise to make it a centerpiece of the 2008 platform and push for it. But now Clinton is on the other side of that equation, with Sanders and his supporters pushing for the more expansive health care coverage and Clinton defending the new status quo.
Some of Clinton's sharpest attacks
throughout the campaign accused Sanders of risking all the expansions achieved through Obamacare. In the heat of the Iowa race, when it appeared Sanders may upset her in the very first contest, Clinton said that Sanders proposal for single-payer health care would risk all the gains made under Obama.
"I don't want us to end up in gridlock. People can't wait. People who have health emergencies can't wait for us to have a theoretical debate about some better idea that will never, ever come to pass," Clinton said.
Black Lives Matter
A year ago, the widespread protests over police shootings which created the Black Lives Matter movement, looked like they could tear the Democratic Party apart -- like the Civil Rights and anti-war protests decades earlier. Black Lives Matter protesters shut down a Sanders rally in Seattle last August
and, partly in response, Sanders hired a top BLM activist to be his national press secretary. After watching the stunning takeover of the Sanders rally, Clinton met privately with BLM protesters and later released video of the meeting.
And at then end of last August, as a preventative measure, the DNC adopted a resolution last August saying that the party stands with BLM protesters.
There will be plenty of splits among Democrats in Philadelphia, but Black Lives Matter does not appear to be one of them.
The dilemma -- accepting super PAC support while blasting the decision that made it possible -- seemed accepted wisdom, but Sanders turned it instead into one of the nastiest battles of the campaign.
Sanders built a movement saying he refused to take money from the "millionaires and billionaires" and promised repeatedly that he would not start his own super PAC. He rarely mentioned her by name, but the campaign finance knocks were aimed squarely at Clinton. The Clinton campaign fired back by noting the nurses union was supporting him with their super PAC.
The party will now have to decide whether opposing the Citizens United decision also means flatly opposing super PACs.
It's not technically a fight for the party's platform, or even one that will be decided in Philadelphia, but what to do with superdelegates -- Democratic party leaders and officials who are not committed based on election results, but instead are free to support whomever they like -- will be one of the biggest fights for the party.
The idea itself -- of party leaders making selections separate from election results -- harkens back to before the reforms that Democrats made in the wake of their last seriously chaotic convention, 1968 in Chicago. And even though the party shifted from leaders and officials calling the shots, a small pocket of them -- so-called superdelegates -- were kept as a way for the party to unify behind a candidate after a particularly nasty primary fight, like, say, this one.
Clinton is all but certain to win the nomination based on the votes of those superdelegates -- the embodiment of the Democratic establishment Sanders and his supporters have railed against. The Sanders campaign has launched a two-track strategy of attempting to flip those superdelegates to supporting him -- with minimal success so far -- while blasting the system itself.
Elleithee, who was a spokesman for Clinton in 2008, pointed out the irony for Sanders: If superdelegates voted in line with their states' results, Sanders would lose. So he has to exploit the system before he could ever abolish it, he said. He argued it might appear they are swinging the nomination to Clinton, but she would win without them.
"I'm not arguing that it's wrong to have a conversation about the role of superdelegates, all I'm saying is that they have never impacted a nomination," Elleithee said.