Sen. Bernie Sanders of Vermont won’t be getting one last debate with Democratic presidential frontrunner Hillary Rodham Clinton before the critical June 7th Democratic primary in California, as he had hoped. But he has extracted concessions from Clinton and party officials that will assure a contentious and “messy” national convention in Philadelphia this summer.

Clinton, who is just 90 delegates shy of locking up what Sanders calls “the rigged” Democratic presidential nomination, rejected an invitation from Fox News on Monday to debate her nemesis Sanders, who is desperately trying to change the narrative of the campaign. Clinton’s campaign spokesperson, Jennifer Palmieri, said in a statement that the former secretary of state’s time would be better spent waging war with presumptive GOP presidential nominee Donald Trump.

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But Sanders is still leaving his mark on this election. Clinton has made major concessions to Sanders in the party’s platform that will all but assure that the democratic socialist will affect a wide range of domestic and foreign policy matters.

Sanders has vowed to carry his campaign all the way to the convention floor, regardless of the delegate count, hoping to somehow persuade scores of “super delegates” to shift their support from Clinton to him. For months, he has highlighted his sharp differences with Clinton over economic policy, health care, Wall Street reforms, the environment and even U.S. policy towards Israel and the Palestinians -- which Sanders complains is tipped too heavily towards Israel.

Sanders was given a say in the choice of five of the 15 members of the platform committee, according to The Washington Post, and he wasted no time Monday in selecting James Zogby, a longtime advocate of Palestinian rights. He also selected

Rep. Keith Ellison of Minnesota, one of his most prominent backers; Bill McKibben, an author and environmentalist, and Native American activist Deborah Parker.

Related: Why Democrats Need Bernie Sanders to Stay in the Race

Feelings run high between the Sanders and Clinton camps, with some polls suggesting that a quarter or more of Sanders’s Democratic and independent supporters would refuse to vote for the more moderate Clinton in the general election.

In the wake of the recent violent clash between Sanders and Clinton forces at a Nevada Democratic state convention, Sanders said that he would "condemn any and all forms of violence.” But he insists on welcoming political newcomers or those with differing views from the status quo at the convention.

"I think if they make the right choice and open the doors to working-class people and young people and create the kind of dynamism that the Democratic Party needs, it's going to be messy," Sanders told the AP.

While the two sides differ sharply on many issues, here are the five that will likely create most of the fireworks at the Democratic National Convention this July:

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Israel and the Palestinians – Clinton, the former secretary of state, understandably has a stake in preserving the status quo in U.S. relations with Israel and the Palestinian authority since she helped to negotiate them, including the November 2012 cease fire between Israel and Hamas. The Democratic Party’s current policy calls for a “just and lasting” Israeli-Palestinian accord that would eventually produce a two-state solution.

However, the platform is silent on the issue of Israeli occupation of Palestinian land and the conduct of Israeli troops in cracking down on violence. Here, Sanders wants a more “even handed” approach to Israeli occupation of land that the Palestinians claim for a future state. Sanders insists that Israeli’s response to the uprising and violence in Gaza and missile attacks on their villages in 2014 was “disproportionate and led to unnecessary loss of innocent life.”

Clinton says that Israel had no choice but to defend itself from missile attacks from the terrorist organizations that control the Palestinian territory. “So, I don't know how you run a country when you are under constant threat, terrorist attacks, rockets coming at you,” she said during an April Democratic debate. “You have a right to defend yourself.”

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National Health Care -- Sanders and Clintons have repeatedly dueled over the future of the Affordable Care Act and other federal health programs, with Sanders pressing for a “single-payer” national health care program to supersede existing programs while Clinton has argued for incremental improvements to gradually extend coverage to all Americans.

Sanders complains that the U.S. is the only major industrialized country without a national health insurance program, and has promoted a Canadian-style national health and long-term care program that would cost an additional $13.8 trillion over the coming decade, according to some estimates. Clinton has been adamant in her support of Obamacare and has dismissed Sanders’s plan to guarantee all Americans health care as too costly and impractical.

However, amid mounting pressure from Sanders and liberal Democrats, Clinton signaled recently that she would be open to allowing some people under the age of 65 to buy into Medicare, the federal health care plan for seniors. Clinton for years has been open to changes and improvements in Obamacare. More recently, she has proposed a number of methods for expanding health care coverage to millions of uninsured Americans and lowering the price of prescription drugs. So clearly there is plenty of room for compromise heading into the national convention this summer.

Breaking up the big banks – There is probably no more politically sensitive issue in the Democratic race than what to do to avert another banking industry crisis and meltdown, if for no other reason than Sanders has relentlessly hammered Clinton for being too cozy with Wall Street and accepting $2.9 million in speaking fees from a dozen banks including Goldman Sachs and Morgan Stanley.

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Sanders and Clinton both stressed during their mid-April debate that they were more than willing to break up big banks that continue to pose a systemic risk to the U.S. and international economy. However, they differed significantly in how they would approach mitigating “too big to fail.”

Clinton says she supports the broad framework created under the Dodd-Frank Act, while Sanders says he would take a much tougher approach by having Treasury officials set a “hard cap” on the size of assets that banks can legally hold and leaving it to bank officials to decide where to cut back. "What the government should say is, 'You are too big to fail, you have got to be a certain size,' and that the banks have got to figure out what they have to sell off," Sanders said during the debate. "I don't know that it is appropriate for the department of the Treasury to be making those decisions."

Clinton, for her part, would take a more nuanced approach, following the strictures of Dodd-Frank. She said it "has to be the judgment of the regulators" whether the government tells banks what assets they have to sell off or leaves it up to the institutions themselves.

Raising the minimum wage – One of the touchstones for Sanders in addressing income inequality in the U.S. is raising the federal minimum wage from $7.25 to $15 an hour. “Millions of Americans are working for totally inadequate wages,” according to Sanders. “We must ensure that no full-time worker lives in poverty. The current federal minimum wage is starvation pay and must become a living wage.”

Related: Clinton -- Trump’s Not Qualified, and Sanders Is Done

Clinton agrees that the current national minimum wage is inadequate, but has advocated a far less generous approach to creating a new national floor on wages. She initially favored raising the federal minimum wage to $12 an hour, amid howls from liberal Democrats, and then subsequently voiced support for state and local level action to set the floor at $15 an hour. Her logic was that while wealthier cities and jurisdictions with higher costs of living – like New York and Los Angeles -- reasonably could set the minimum wage at $15 an hour, poorer cities and regions should not have to be forced to follow suit under a federal mandate.

However, Clinton began to bob and weave when she was pressed on her views during the last Democratic debate. Asked by the moderator whether she would sign a bill raising the national minimum to $15, Clinton replied, “Of course I would. I have supported the Fight for $15,” adding that she had recently stood with New York Gov. Andrew Cuomo and labor leaders in support of the increase in New York State.

By time she completed her answer, it was clear that Clinton continued to support a tiered system in which Congress would raise the minimum wage to $12 an hour we will set a national level of $12, while urging any state or local jurisdiction “that can go above it to go above it.” Sanders is dismissive of what he considers to be Clinton’s double-talk, and will press on at the convention for a $15 an hour minimum wage plank to the platform.

Carbon Tax -- While Sanders and Clinton basically agree that traditional energy sources such as coal are dirty and that the future is in renewable energy, they are split on how best to get there.

Sanders has been pushing for a European-style tax on carbon emissions to curb climate change and has urged Clinton to come around to his point of view if she is “concerned” about the environment. The former Secretary of State hasn’t proposed putting a price on greenhouse gas emissions, preferring to follow the course set by President Obama. He has sought to rein in pollution through regulation and other steps, like the Paris climate agreement that pledged 175 countries to cut back to their emissions.