Bernie Sanders has been characterized throughout his career as an idealistic outsider with unrealistically far-reaching policy proposals that go far beyond what's politically feasible.

It turns out he'd like his top allies at the Democratic convention in Philadelphia this July to be of a similar cast.

On Monday, after a major concession from the Democratic National Committee gave him the ability to do so, Sanders announced his five choices for the "platform committee" that will write the party's officials positions.

His selections — radical black intellectual Cornel West and hardcore climate activist Bill McKibben, Congressional Progressive Caucus co-chair Keith Ellison, Muslim rights spokesperson James Zogby, and Native American tribal rights leader Deborah Parker — are primarily progressive firebrands known, like Sanders, for rejecting half-measures and seeking to exert pressure from outside the mainstream.

The rest of the committee will include six members chosen by Hillary Clinton and four chosen by DNC chair Debbie Wasserman Schultz. So, for practical purposes, it's not clear how much Sanders's choices will really be able to rewrite the party platform.

Still, the split in the platform committee sets up what could be an explosive confrontation at one of the Democratic Party's primetime moments ahead of the general election.

Clinton's choices are deeply enmeshed in Democratic politics — they'll be much more likely to play ball with what the party wants, and likely unwilling to cause too much heartburn for Democrats looking to unify around a set of core issues.

Sanders's choices will be much less afraid to whack the hornet's nest. Like Sanders himself, they've tended to rail against the party's compromises as activists.

In other words, they're used to being outsiders. In Philadelphia, they'll be getting a seat at the table.

So who are these people?

One could imagine any number of directions for Sanders to go with his choices for the platform committee: union officials who can share his impulses on trade; little-known wonkish progressives in academia; the Ben & Jerry's ice cream moguls who helped fundraise for his campaign.

Instead, as Clare Foran notes in the Atlantic, Sanders went in a different direction — choosing people who perhaps highlight his difference in political theory with Clinton rather than narrow policy disagreements.

At least three of Sanders's five picks have been arrested in the past few years for acts of civil disobedience, while Clinton's are more likely to have ties to existing Democratic institutions or center-left technocratic policy circles.

"Clinton has a reputation as a party insider with deep ties to the Democratic establishment, while Sanders is known as an agitator unafraid to challenge political norms," Foran says. "Their representatives on the platform-drafting committee seem to fit that same mold."

Perhaps Sanders's most radical choice for the committee is civil rights activist Cornel West, a Princeton professor who has called Barack Obama America's "first 'niggerized' president" afraid to tackle white supremacy and Clinton a "milquetoast neoliberal."

There's also Bill McKibben, an environmental activist best known for leading the 350.org group seeking to cap global carbon emissions. McKibben has been sounding the alarm the loudest on climate change as the biggest issue facing the planet.

Sanders also tapped Keith Ellison, a Minnesota official who is one of two Muslims in Congress. Ellison is the co-chair of the Congressional Progressive Caucus and became one of the earliest Sanders endorsers in Congress.

Sanders's other two choices are James Zogby, president of the Arab-American Institute, and Deborah Parker, a tribal leader and activist for Native American rights.

Among Clinton's picks, the most prominent is Neera Tanden, a longtime Clinton aide who is now president of the center-left think tank the Center for American Progress.

Unlike Sanders, Clinton is tapping the ranks of former government officials, including Wendy Sherman, who was the fourth-ranking member in the State Department; and Rep. Luis Gutiérrez, who was the White House Energy and Climate Change Policy director and one of the loudest voices on pushing for immigration reform. (It's worth noting Gutiérrez has also been arrested over his chief cause.)

Her other two picks were Ohio Rep. Alicia Reece, who first took office in 2010, and Paul Booth, an executive assistant at the American Federation of State, County, and Municipal Employees union.

How Sanders's choices could influence the Democratic Party

Sanders's choices suggest several points of departure with the party, but it's unclear if the issues he's advancing are the same ones that drew voters to his campaign. (Sanders's ability to name part of the DNC's committee is "unique" in the party's history, according to the Washington Post.)

Writing in the New York Times on Monday, for instance, political scientists Christopher Achen and Larry Bartels argue that we don't know if Sanders's voters support his specific policy positions just because they voted for him:

Many analysts have argued that Mr. Sanders’s surprising support signals a momentous shift to the left among Democrats. But wishing does not make it so. Decades of social-scientific evidence show that voting behavior is primarily a product of inherited partisan loyalties, social identities and symbolic attachments. Over time, engaged citizens may construct policy preferences and ideologies that rationalize their choices, but those issues are seldom fundamental.

But Ryan Enos, a professor at Harvard University, notes in an interview that Sanders could still be leaving his imprint on the party.

"We know that voters in the public get pulled in the direction of the people with the microphone," Enos says. "If someone gets up there and tries pulling some issue to the left, the party can move in that direction."

Giving vocal activists like McKibben and West a seat at the table, in other words, might not translate into concrete policy changes in the Democratic platform, and their issues may not be why Sanders rose to prominence in the first place.

But by amplifying their voices, it could certainly begin moving the thinking of the rank and file in their direction.

"The people he's picked really could pull the party to the left," Enos says, "and probably in a way that makes Clinton a little uncomfortable."