Sen. Bernie Sanders was given unprecedented say over the Democratic Party platform Monday in a move party leaders hope will soothe a bitter split with backers of the longshot challenger to Hillary Clinton — and Sanders immediately used his new power to name a well-known advocate for Palestinian rights to help draft Democratic policy.

The senator from Vermont was allowed to choose nearly as many members of the Democratic Party platform-writing body as Clinton, who is expected to clinch the nomination next month. That influence resulted from an agreement worked out this month between the two candidates and party officials, the party announced Monday.

Clinton has picked six members of the 15-member committee that writes the platform, and Sanders has named five, the Democrats said Monday ahead of an expected announcement by the Democratic National Committee.

The math is based on the number of popular votes each has received to date, one official said. Debbie Wasserman Schultz, chair of the DNC, will name four. The candidates’ choices were selected in consultation with the campaigns and the DNC from larger slates of 12 and 10 suggested by the campaigns.

Sanders’s slate includes James Zogby, a longtime activist for Palestinian rights as well as a DNC member and official. Zogby currently co-chairs the party’s resolutions committee. His inclusion is a sign of Sanders’s plans to push the party’s policy on Israel toward what he has called a more even-handed approach to the Palestinian cause.

With reporters in California after a rally Monday, Sanders celebrated the arrangement.

“With five good members on the platform-drafting committee,” Sanders said, “we will be in a very strong position to fight for an economy that works for all of our people, not just the one percent; to fight to break up the large banks on Wall Street, who in my view now have much too much economic and political power. We will be in a position to fight for a carbon tax, so that this nation can begin to lead the world in aggressively addressing climate change. We will be in a position to fight to have the United States join the rest of the industrialized world in guaranteed health care as a right.”

“This is unique in terms of the makeup of the platform drafting committee,” said James Roosevelt, co-chairman of the DNC’s rules and bylaws committee. “What it acknowledges is that the Democratic Party is committed to encompassing the broad range of views that Democrats have surfaced in this very substantive campaign between Secretary Clinton and Senator Sanders. And I think that is unusual but it is also very necessary because a unified Democratic Party will be strengthened by a full hearing for all views.”

DNC rules allow the chairman to pick the entire slate of 15 people who govern the platform that will be presented at the party convention in July. Past chairmen have done just that, in consultation with the White House or the winning Democratic candidate.

The change was made to be inclusive of Sanders supporters after the strong liberal challenge he mounted during a long and sometimes bitter primary. A main complaint of Sanders’s supporters is that party rules and procedures disproportionately benefit Clinton. Some Sanders backers claim the system was “rigged” from the start to exclude a challenger.

The procedural concession represents an outreach from party elders aware that Sanders has tapped into a powerful anti-
establishment current and concerned that it will be difficult to unite Democrats behind Clinton.

The platform committee is among the most important party bodies, since it writes the policy on which the presidential candidate runs and around which Democrats are supposed to rally. The platform is nonbinding, however, and presidents have ignored parts of it in the past.

Rep. Elijah E. Cummings of Maryland, who will chair the committee, was named by Wasserman Schultz. Most others named by Wasserman Schultz and Clinton are party stalwarts or Clinton supporters — the establishment Sanders has railed against to great effect. Sanders’s picks include people from outside the usual sphere of party influence, including a Native American activist and author and racial justice activist Cornel West.

Zogby, president of the Arab American Institute in Washington and a frequent commentator on Arab-Israeli issues, previously served on the larger platform committee that will approve the document, but this is the first time he has served on the drafting committee, he said.

Sanders’s approach to Israeli-Palestinian issues is in line with most Democrats’ views, Zogby said in an interview. Sanders wants American policy to respect both Israel’s security concerns and Palestinian rights, he said.

“You need to find a way to meet the needs of both. To say we will satisfy one without the other is a recipe for failure” as peacemakers, Zogby said.

Writing on the institute’s web site Saturday, he noted recent shifts in the Israeli government under Prime Minister Benjamin Netanyahu that consolidated Netanyahu’s right-wing power base.

“His behavior has been shameful, but so too is the extent to which Israelis, Americans and others continue to enable his malevolent rule,” Zogby wrote.

Sanders also named Rep. Keith Ellison of Minnesota, among his most prominent elected backers, author and environmental activist Bill McKibben and Native American activist Deborah Parker.

The Clinton campaign’s choices are Wendy Sherman, a former top State Department official and Clinton surrogate; Neera Tanden, president of the Center for American Progress and a longtime Clinton confidante; Rep. Luis V. Gutiérrez of Illinois; Carol Browner, a former director of the White House Office of Energy and Climate Change Policy and former head of the Environmental Protection Agency; Ohio state Rep. Alicia Reece; and Paul Booth of the American Federation of State, County and Municipal Employees union.

Wasserman Schultz also named former congressman Howard Berman of California; Rep. Barbara Lee of California; and executive Bonnie Schaefer.

Each campaign also has a non-voting representative at committee meetings.

“We’re pleased that the upcoming Democratic convention will ensure supporters of Senator Sanders are well represented in the drafting of the party’s platform,” Clinton spokesman Brian Fallon said. “The Democratic Party historically has been a big tent, representing a diverse coalition, and Hillary Clinton is committed to continue welcoming different perspectives and ideas.”

David Weigel in Los Angeles contributed to this report.