In France, Marwan Barghouti is called "the Palestinian Nelson Mandela," an imprisoned militant turned bookworm who talks of peace when he gets out. In the West Bank and Gaza, many call him the heir to Yasser Arafat, so popular that polls routinely show him winning the presidency of the Palestinian Authority, even while he remains behind bars. Israelis know him as a mass murderer, serving five life sentences for sending suicide bombers to a Tel Aviv fish market and a Jerusalem mall.

And in the U.S.? Few Americans have heard of the stocky, mustachioed militant whose shadow looms over the most persistent questions of the Palestinian movement — Who's in charge? What comes next

"The priority in these circumstances and in light of the current changes is for peaceful resistance," Barghouti tells TIME in written replies to questions carried into Israel's Hadarim prison by his attorney. "For more than five years the Palestinian factions have stopped their armed operations except for self-defense. At this point in time, Palestinians give the priority to political and diplomatic efforts, peaceful resistance and international isolation of Israel to achieve freedom and independence."

The qualifiers — "at this point in time" and "in these circumstances" — capture the duality that has characterized the Palestinian movement for decades: Negotiation or resistance? Talk or fight?

Barghouti has done both, but he insists violence was an option forced on Palestinians by Israel. "It is important to note the first Palestinian intifadeh followed almost the same approach as the Arab revolutions, but was met by severe Israeli brutality and suppression resulting in the loss [hundreds] of Palestinian lives."

Barghouti's popularity is grounded in years of grassroots organizing, and his ability to reach across the factional divides that bedevil Palestinian politics. A member of secular Fatah — and, significantly, a Fatah member who remained among his people while others spent years in relatively lavish exile — his name is prominent on the list of prisoners that Hamas wants released in exchange for Gilad Shalit, the young Israeli soldier kidnapped five years ago. "It's very important to note Marwan Barghouti is not a leader sitting in an office," says his wife Fadwa, seated at desk in her own. The Campaign to Free Marwan Barghouti and All Palestinian Prisoners has a suite atop a new office tower overlooking Arafat's tomb. "He's a leader in the streets," she says, "Everywhere in the streets." (See photos of the Palestinian 'Day of Rage.')

Six years ago he was also on the ballot, running for Arafat's post as president of the Palestinian National Authority while behind bars. He withdrew in favor of Mahmoud Abbas, the Western favorite widely known as Abu Mazen. Barghouti says he emphatically supports Abbas' strategy of negotiating with Israel for an end to the occupation while building the institutions of statehood championed by PA prime minister Salam Fayyad. But Abbas, 76, insists he will not run again in elections promised within the year.

Barghouti's positions all but define the Palestinian mainstream. The reconciliation announced in Cairo was presaged in 2006 by Prisoner's Document, a watershed statement of shared intent initialed by Barghouti and jailed leaders of all other major factions. The declaration calls for negotiating with Israel for a Palestinian state based on the 1967 borders. "He might be even more pragmatic than Abu Mazen and Fayyad," says Amos Oz, the acclaimed Israeli novelist who sent the prisoner an Arabic translation of his memoir, A Tale of Love and Darkness. "This story is our story," Oz inscribed on the copy he sent to Barghouti. "I hope you read it and understand us better, as we attempt to understand you. Hoping to meet soon in peace and freedom."

Inside the prison, Barghouti spends half of his day reading, writing or teaching other prisoners, most of whom share communal blocs and elect leaders according to faction. In ways the setting recalls Robben Island, the apartheid South African penal colony that doubled as a university for leaders of the African National Congress. But, says Oz, "I don't like the comparison. Mandela never mentioned the right way to put an end to apartheid was to kill civilians, and Barghouti did." Mandela did, however, create the ANC's armed wing, arguing that nonviolence had its limits. To prepare, the future Nobel laureate read The Revolt, an account by another future Nobel peace laureate, Menachem Begin, of the underground Jewish resistance that carried out bombings against the British government in Palestine in the 1940s. Begin was Prime MInister of Israel from 1977 to 1983. Says Oz: "There are so many heads of state who were involved in armed struggle before they became heads of state — it's not unusual in history — including some of the leaders of the state of Israel." (See photos of clashes between Palestinians and Israeli soldiers.)

Comparisons with Arafat are more apt. Barghouti's graffito portrait stands beside Arafat's likeness on the most prominent stretch of The Wall, beside the Qalandia checkpoint that separates Ramallah from Jerusalem. The younger man is shown in his iconic moment, hoisting his manacled wrists overhead in both defiance and triumph, his incarceration available as a metaphor for Palestine's. "He's a man," says Osama Shougan, 21, who stands a little straighter at the mention of Barghouti's name during an interview in Ramallah's downtown vegetable market. "He's a leader."

Israeli admirers are harder to find, but among his most regular visitors in prison has been Haim Oron, longtime head of the Meretz party, a stalwart of the left wing that in Israel is also known as "the Peace Camp." Oron left politics earlier this year, but it could also be argued that Israeli politics left the Peace Camp years ago and Barghouthi was a reason. Once a fixture on the evening news professing Israel had a partner in the Oslo Accords, Barghouthi was also assembling an underground military wing, Tanzim, that carried out some of the worst attacks of the Second Intifadeh. "I think he's maybe the most important Palestinian leader," Oron says. "I think that he's a partner. And he's also a friend. A strong word, but a friend." If the question is violence, Oron has a question of his own. "You know a Palestinian official who refutes resistance, officially? Give me the name," he says, "The resistance option is always on the table. The question is if you choose it."