BEIRUT (AP) — Lebanese President Michel Suleiman formally accepted on Saturday the resignation of the prime minister, who stepped down blaming government infighting during a time of rising sectarian tensions.

Prime Minister Najib Mikati submitted his written resignation to the president after announcing he was stepping down the day before, taking the nation by surprise. Suleiman asked that his government assume a caretaking role while a new government is being formed.

Mikati’s unexpected resignation throws the country into uncertainty at a critical time and threatens to leave a void in the state’s highest ranks amid sporadic violence enflamed by the civil war in neighboring Syria.

It opens the way for what is expected to be prolonged political jockeying as parliamentary blocs try to build a majority coalition to choose a new prime minister.

"I hope that this resignation will provide an opening in the existing deadlock and pave the way for a (political) solution," he said, following his meeting with Suleiman Saturday.

Mikati has been prime minister since June 2011, heading a government dominated by the Shiite militant group Hezbollah and its allies, many of whom have a close relationship with Syria.

Their main rivals are a Western-backed coalition headed by former Prime Minister Saad al-Hariri, son of Rafik Hariri, who was also Prime Minister and was killed in a truck bombing in 2005.

A Harvard-educated billionaire, Mikati was chosen to lead the government after Hezbollah forced the collapse of Lebanon’s previous, pro-Western government over fears a U.N.-backed tribunal investigating the killing of the elder Hariri would indict Hezbollah members.

But Mikati’s relations with Hezbollah have never been smooth. He has rejected the notion that he serves Hezbollah or that his government will act as an Iranian proxy. Hezbollah accuses him of loyalty to the rival camp.

He stepped down Friday to protest the parliament’s inability to agree on a law to govern elections set for later this year, as well as the refusal by Hezbollah and its allies in the cabinet to extend the tenure of the country’s police chief, Maj. Gen. Ashraf Rifi, who at 58 is about to hit the mandatory retirement age for his rank.

Rifi, like Mikati, is a Sunni Muslim who is considered a foe by Hezbollah.

In his speech Friday, Mikati said that if Rifi is not allowed to stay on, his departure would send the police department into "a vacuum."

Underpinning the political crisis are Lebanon’s hugely sectarian politics and the fact that the country’s two largest political blocs support opposite sides in Syria’s civil war. Lebanon and Syria share a complex network of political and sectarian ties, and many fear that violence in Syria will spread to Lebanon.

There were signs of rising tensions before the resignation.

Gunmen who support and oppose Syrian President Bashar Assad clashed Friday in the northern Lebanese city of Tripoli, leaving six people dead and more than 20 wounded, according to the state-run National News Agency. Clashes between the Sunni neighborhood of Bab Tabbaneh, which supports Syria’s rebels, and the adjacent Alawite neighborhood of Jabal Mohsen, which supports Assad, have broken out repeatedly in recent months. Assad is Alawite, a Shiite offshoot sect.

Also in Tripoli, the Lebanese army said a soldier was killed and several others wounded during an army raid to capture several gunmen.

Mikati’s resignation may be an attempt to boost his credentials among his fellow Sunni Muslims ahead of the upcoming election and amid the violence in Tripoli, his hometown.

Some Lebanese media have speculated that his decision to step down was based on "insinuations" from the U.S. and its allies to clear the way for an anti-Hezbollah majority, or at least a neutral government. Mikati in his speech denied that he had been pressured by foreign powers, insisting that it was a "personal choice without any intervention from anyone."