HANGZHOU, China — President Barack Obama's emissaries spent much of Sunday talking with Russian officials about how to quell the violence in Syria, but the president all but shrugged his shoulders when asked about the prospects of a successful deal with Russian President Vladimir Putin.

“Given the previous failures of cessations of hostilities to hold, we approach it with some skepticism,” Obama said, “but it is worth trying.”

Hours later, Obama engaged in delicate talks with Turkish President Recep Tayyip Erdogan, whose military has clashed with U.S.-backed fighters in Syria.

“We discussed ways in which we can further cooperate in that regard,” Obama said after his meeting with the crucial NATO ally, whose country is still reeling from a failed military coup and a wide domestic crackdown on suspected instigators.

Obama's final presidential appearance at the Group of 20 world leaders summit here has been a complicated waltz of diplomacy with an array of difficult partners.

Despite the strained relationships, Obama is obligated by a long list of simmering world problems to engage with leaders from Erdogan to Putin, with whom White House officials say he is planning to meet. “You don't negotiate deals with your friends,” his oft-stated mantra goes, “you negotiate them with your enemies.”

Obama got a rough welcome to China on his 10th and final presidential tour of Asia.

As Air Force One taxied on the tarmac, Chinese officials were refusing to let the U.S. Secret Service wheel stairs to the plane so that Obama could make his usual grand entrance from the front door. Instead, they ended up wheeling short stairs to a side door, where the traveling White House press corps could barely see him to record the moment.

An official of the Chinese delegation yelled at White House staff for allowing the press in the area at all and then physically blocked national security adviser Susan Rice and her deputy from moving closer to the arrival scene.

“They did things that weren't anticipated,” Rice said later.

Much of the difficulty Obama is encountering on his trip was anticipated, however. Turkey, for example, repeatedly has tried to blame the U.S. in the weeks since the failed military-led coup against Erdogan.

Erdogan's government has complained about the U.S. failure to extradite Fethullah Gulen, the Turkish cleric who lives in self-imposed exile in Pennsylvania. Erdogan blames him for plotting the coup. Gulen denies the charge.

On Sunday, Erdogan was politely oblique. The U.S. and Turkey should adopt a “common attitude” against terrorism, he said.

Obama reassured the Turkish leader that the U.S. will work to make sure the parties responsible for the coup come to justice. He condemned the overthrow before quickly noting the need to “further cooperate.”

U.S. officials say they are awaiting sufficient evidence to justify Turkey's request for the extradition of Gulen.

In the same way, Obama's White House aides maintained a sense of reserve as Secretary of State John Kerry met with Russian Foreign Minister Sergey Lavrov in an effort to work out a cease-fire between Syria's government and at least some rebel groups as well as possible enhanced military cooperation between Russia and the U.S. in Syria.

State Department officials were optimistic that a deal would come together. But as Obama spoke to reporters early in the day, the president was doubtful.

Every experience he has had with Putin tells him to be skeptical about whether a deal is possible and whether Putin would stick to one, said a senior aide, speaking anonymously to comment on diplomatic talks.

Kerry said he and Lavrov have worked out a number of technical issues. They plan to reconvene Monday.

With Chinese President Xi Jinping, Obama and his staff have concluded that the only breakthrough they will achieve is the climate deal they ratified Saturday.

The White House believes that on all the other important items on the Chinese-U.S. agenda — trade, cooperation on cybersecurity, human rights — Xi has determined it is not in his interest to work with Obama.

“You don't develop real trust between the U.S. and China,” said Jeffrey Bader, a former China adviser to Obama. “What you can develop is transparency, where you can say, ‘I know what he thinks and I know where he's going.' That's what the president has done.”

Los Angeles Times reporter Tracy Wilkinson contributed.

christi.parsons@latimes.com