STATE DEPARTMENT - Turkey is central to U.S. and European efforts to get opponents of Syrian President Bashar al-Assad to possibly come to the peace table. But growing domestic unrest in Turkey could complicate Ankara's efforts at Middle East diplomacy.

Turkey is a front-line state in the Syrian conflict.

Turks have been the victims of bombings along the border and host to more than 200,000 Syrian refugees.

Turkish Foreign Minister Ahmet Davutoglu has been working to unite the Syrian opposition in hopes of getting them to peace talks, which have been put off until at least July.

"Turkey occupies a critical position in the way the Syrian conflict might unfold: whether negotiations were to begin or whether the West, including Turkey, were to agree to take a more active policy in trying to contain the activities of the Assad regime," said Analyst Steve Heydemann, U.S. Institute of Peace.

But now Turkey's attention to the Syrian conflict is being diverted by days of anti-government political unrest inside Turkey.

U.S. Secretary of State John Kerry said the domestic backlash will not deter Ankara from its role in Syrian diplomacy. "It’s not the first time any government has faced this kind of challenge," he said. "And I do expect Foreign Minister Davutoglu and the prime minister to remain engaged in the effort to try to resolve what is happening in Syria."

Prime Minister Recep Tayyip Erdogan has been a leading critic of the Syrian regime.

But analyst Heydemann said the longer the war continues, the tougher it is for Turkey to keep backing the opposition.

"Turkey is going through a period in which I think they're feeling a bit of buyer's remorse about the level of support they've provided to the opposition of the past couple of years," he said. "They're beginning to rethink whether their antagonism toward the Assad regime is really paying off for them or not."

Erdogan said there is no going back on Turkey's involvement in inter-connected Mideast crises. "In this region, the issue of Syria, the issue of Palestine and Israel are the problem that need to be resolved, in order to have perpetual peace in the Middle East," he said.

Israeli-Turkish relations suffered three years ago when Israel assaulted a Turkish boat with peace activists taking food and other staples to the Gaza Strip.

Recently Erdogan has criticized Israeli airstrikes on Hezbollah supply routes in Syria, complicating U.S. efforts to improve ties between Turkey and Israel.

"We are not going to tell the Israelis that if they feel a critical security red line in Syria has been crossed they should not act. But if we endorse, even if we endorse tacitly, Israeli action in Syria, it makes it all the harder for Erdogan and for Turkey to sustain that effort to rebuild ties with Israel," said Heydemann.

Even as U.S. officials express concern about the use of force against Turkish anti-government demonstrators, the two countries continue to work closely towards talks on a transitional authority in Syria.