BAQUBA, Iraq — The governor has fled this uneasy city. Half the members of the provincial council are camped out in northern Iraq, afraid to return to their offices. Peaceful protesters fill the dusty streets, though just days ago angrier crowds blockaded the highways with burning tires and shattered glass.

All of this because the local government here in northeastern Diyala Province recently dared to raise a simple but explosive question, one that is central to the unrest now surging through Iraq’s shaky democracy: Should a post-American Iraq exist as one unified nation, or will it split into a loose confederation of islands unto themselves?

A dire political crisis exploded in Baghdad this week, after an arrest warrant was issued against the Sunni Arab vice president, Tariq al-Hashimi, accusing him of running a death squad. But years of accumulated anger and disenfranchisement are now driving some of the country’s largely Sunni Arab provinces to seek greater control over their security and finances by distancing themselves from Iraq’s Shiite leaders.

Many Sunni leaders have rallied to the cause while top Shiites in Baghdad have fought the efforts, aggravating the sectarian divisions among the country’s political elite.

“They feel that they have no future with the central government,” said Deputy Prime Minister Saleh al-Mutlaq, a prominent Sunni.

This development comes at a moment of rising tensions and could herald a near-breakdown of relations between the countryside and the leaders behind the concrete walls and concertina wire guarding Baghdad’s Green Zone. It has splintered communities within provinces along religious lines, while deepening the sense of political uncertainty pervading Iraq in the days after the American military’s withdrawal.

“We’ve reached a point where the exasperation with the entire political process is so big in Sunni majority areas,” said Reidar Visser, an expert on Iraqi politics and the editor of the blog historiae.org. “They are just fed up and disillusioned.”

On Friday, thousands of protesters marched through largely Sunni cities to condemn the warrant for Mr. Hashimi’s arrest. In Samarra, where the destruction of a Shiite shrine in 2006 set off waves of violence, 2,000 demonstrators filled the streets after Friday Prayer, waving signs that declared, “The people of Samarra condemn the fabricated charges against Hashimi.”

The schism is one thread of a growing battle between Prime Minister Nuri Kamal al-Maliki, a Shiite, and politicians from the political opposition and Iraq’s Sunni Muslim minority.

Security forces who take orders from Mr. Maliki — sometimes personally — have arrested dozens of people tied to opposition politicians in recent weeks. The government accused Mr. Hashimi, the Sunni vice president, of running a death squad from his offices in central Baghdad, a charge he denies. And Mr. Maliki has urged Iraqi lawmakers to unseat his own deputy, Mr. Mutlaq, who frequently inveighs against the prime minister.

A leading political coalition supported by many Sunnis and secular Iraqis has boycotted Parliament, refusing to attend sessions, and its ministers and lawmakers have threatened to resign en masse. An American-backed partnership government uniting Iraq’s three main factions — the Shiite majority, Sunnis and Kurds — appears poised to fall.

That discord is resonating in the largely Sunni provinces around the capital, places that once hewed to a rigid nationalism cultivated by Saddam Hussein.

In recent months, Anbar, Salahuddin and Diyala Provinces have each pushed for a public vote on creating their own regional governments.

Mr. Maliki has pushed back harder. His supporters contend that the movement threatens to destabilize the central government. They say that regions controlled only by local security forces would provide safe havens for Al Qaeda in Iraq, the Baath Party and other Sunni-aligned militant groups at a tenuous moment so soon after the American military withdrawal.

During a trip to Washington this month, Mr. Maliki was asked in a meeting about the movement for greater regional control and offered a brusque reply, according to an American who met with Mr. Maliki during his visit.

“His response was: ‘Everything those people are doing is illegal. The only way to deal with them is through a legal process, and not a political process,’ ” said the American, who asked to remain anonymous to avoid jeopardizing access to Iraqi leaders. “This is not a guy who has any interest in compromising.”

Early Friday morning, Iraqi police commandos arrested a leading advocate of Salahuddin Province’s push for regional status and seized his computer and reams of documents, security officials said. They did not say why he had been detained.

The provinces are not seeking a total divorce from the rest of Iraq, just a wider separation in the mold of Kurdistan, the relatively prosperous and safe area in northern Iraq. The Kurds, who have lived for decades as a people apart from the rest of Iraq, have their own Parliament and president, command their own security forces and have signed lucrative oil deals with foreign companies without Baghdad’s approval.

It is not a new idea. Iraq’s Constitution gives provinces the right to carve out their own regional governments. In 2006 and 2007, during Iraq’s civil war, Vice President Joseph R. Biden Jr., then the chairman of the Senate Foreign Relations Committee, suggested partitioning the country into three federal states to calm the sectarian bloodshed.

But could Iraq still stand if it were divided into Kurdistan, Shiitestan and Sunnistan? Even raising the issue unleashes a torrent of emotion.

On Dec. 12, a majority of the members of the Diyala provincial council announced that they were asking Iraq’s central government to hold a referendum on whether the province could form its own semiautonomous region. Diyala is about 60 percent Sunni, 20 percent Shiite and 20 percent Kurdish, and its government roughly reflects that breakdown.

Distrust of the central government runs deep here among the snaking rivers and palm plantations that once served as battlegrounds and hide-outs for Qaeda insurgents. Last year, three of the Sunni members of the provincial council were thrown into jail by Iraqi security forces. Others were threatened.

But the abrupt announcement of a potential Diyala region angered and frightened some of the province’s Shiites. It was read as a power grab that would put Shiites and Kurds in the province at the mercy of unknown new security forces, and could presage the fragmentation of Iraq.

On Dec. 15, about 1,000 outraged demonstrators, most of them Shiites, streamed past the Shiite-dominated national police forces and into the provincial council’s headquarters. They occupied the building for a few hours, then set up roadblocks and tents in the streets. Half the city’s elected officials fled for safety.

Protesters said they had acted spontaneously, but several Sunni officials believed that Iraq’s central government had mobilized the protesters and stoked their outrage to kill the proposal.

“We left the city because of the chaos and insecurity,” said Rasim al-Ugaili, a member of the provincial council who supported the proposal for a new region. “We feared for our lives.”

A few days later, the roads were clear, but the fate of the Diyala region was anything but. The Kurds on the provincial council withdrew their support for the referendum after the protests erupted, and much of the council was still missing.

The deputy governor, Furat al-Tamimi, was filling in until his boss returned. Mr. Tamimi, a Shiite, said he was pleased to see the banners and protesters shouting passionately through the afternoon. “This is all about democracy,” he said.