BEIRUT (AP) — Syria’s main opposition group is launching its most serious attempt yet to form a rival government to President Bashar al-Assad’s regime, convening in Turkey on Monday to choose an interim prime minister for areas the rebels control.

Twelve candidates are running, including economists, businessmen and a former Syrian Cabinet minister.

Some warn setting up such a government could close the door to negotiating an end to Syria’s civil war and instead harden the battle lines even more.

Another obstacle is asserting the authority of a government picked by the largely exile-based opposition, especially in areas where Islamic extremist militias dominate.

The opposition Syrian National Coalition needs to take the reins in increasingly chaotic rebel-held areas where many services have broken down, but doing so means taking a political risk, said University of Oklahoma professor Joshua Landis.

“Obviously (the opposition) has been very frightened of trying, because it does not have a real social base on the ground, and it is worried that if it fails, it will get egg on its face,” said Landis, who runs a blog called Syria Comment.

The deadlocked Syria conflict, which has claimed 70,000 lives and displaced about four million people, entered its third year this weekend.

Leading members of the coalition are meeting in Istanbul, Turkey, on Monday and Tuesday to pick a prime minister who would put together the interim government, said coalition spokesman Khalid Saleh. A vote is expected by Tuesday, he said.

Twelve candidates have been nominated, though the list could shrink if not all accept their nominations, Saleh said. The coalition released 10 names on Sunday but is not publishing the names of two contenders who live in areas under government control, he said.

Among the candidates are Osama Kadi, the coalition’s economic adviser from London, Ontario in Canada; Ghassan Hitto, a longtime IT manager who recently moved from Dallas, Texas to Turkey; Assad Asheq Mustafa, a former Syrian agriculture minister and former governor of Syria’s central Hama province, and Walid al-Zoabi, a real estate entrepreneur from Dubai.

Saleh described the candidates as technocrats. “Each has a minimum of 15 to 20 years of experience in his field,” he said.

The 72 members of the coalition’s general assembly are eligible to vote. If no candidate gets at least 37 votes in the first round, the top two would compete in a second round, Saleh said.

The Syrian government has portrayed those trying to topple it as foreign-led terrorists. The conflict erupted in 2011, initially as a largely peaceful uprising that, in the face of a harsh regime crackdown, turned into an armed insurgency and then into civil war.

Issam Khalil, a legislator from al-Assad’s ruling Baath Party, echoed the regime’s position that the opposition is pursuing foreign interests and is trying to “implode Syria from the inside.” Those meeting in Istanbul want to intensify the conflict in Syria, not end it, he said Sunday.

The U.S. has been cool to the idea of a rival government in the rebel-held areas, saying the focus should be on a political transition.

Under a plan endorsed by the international community last year, al-Assad supporters and opponents would propose representatives for a transition government, with each side able to veto candidates. However, the plan did not address the key question of al-Assad’s role.

Most in the Syrian opposition rule out negotiations with al-Assad, even on the terms of his departure from office.

Last week, U.S. Secretary of State John Kerry affirmed his support for the plan, saying that only a transitional government accepted by both the opposition and the al-Assad government can allow Syrians to determine their future.

The leader of the Syrian opposition coalition, Mouaz al-Khatib, has also suggested he opposes the formation of a rival Syrian government, saying he feared it would deepen divisions in Syria.

Breaking with opposition consensus, the 52-year-old former preacher provoked a backlash last month when he offered to hold talks with members of the regime if it would help end the bloodshed.

The formation of the interim government was put off twice over such disagreements, but Saleh said coalition members voted last month to go ahead with the election. Al-Khatib, while still opposed, is deferring to the majority, Saleh said.

Analyst Fawaz A. Gerges said that the move is likely to block a political solution.

“By electing an interim Cabinet, the Syrian opposition will put an end to any possibility for a negotiated settlement with the Syrian regime,” said Gerges, director of the Middle East Center at the London School of Economics. “They’ve decided to fight all the way.”

With an interim government in place, the “war option would win over diplomacy,” Gerges said.

It’s not clear where an interim government would be able to operate.

The regime routinely attacks rebel strongholds with airstrikes and artillery, and any gathering of senior opposition politicians would be a prime target. More likely, government members would shuttle between Turkey and Syria, as some rebel military chiefs do.

Acceptance is another challenge.

In recent months, Islamic extremist militias, particularly the al-Qaida-linked Jabhat al-Nusra, have asserted dominance in key battle areas.

Al-Nusra and other Islamic extremist fighting groups don’t recognize the authority of the Free Syrian Army and might not be inclined to take orders from an interim government.

Saleh played that down, saying that 85 percent of the fighting forces recognize the Syrian National Coalition. Once the government moves into Syria and starts providing services, “doubts will just vanish,” he said.

Landis predicted that the interim government would face a rough start. Trying to assert authority “is a recipe for conflict, no doubt about it,” he said, “but they’ve got to get down to the towns and offer a real alternative.”

Associated Press writers Barbara Surk in Beirut and Albert Aji in Damascus, Syria, contributed.

Copyright 2013 The Associated Press.