ISTANBUL — President Recep Tayyip Erdogan of Turkey, holding a rare meeting with international journalists, said on Thursday that he expected to resolve disagreements with the United States, particularly his purchase of the Russian S-400 missile system, in a one-on-one meeting with President Trump at the end of the month.
The two leaders are expected to meet on the sidelines of the Group of 20 summit meeting in Osaka, Japan. Officials said they may also seek to finalize plans for Mr. Trump to visit Turkey in July.
Mr. Erdogan, who last gave an interview to an American newspaper in 2012, held the briefing with journalists just days before a rerun of a critical election for Istanbul mayor. The candidate for his Justice and Development Party, known as A.K.P., lost that race in March, and polls suggest he could lose again on Sunday.
But other than rejecting those polls, and insisting that he would accept the results even if the opposition wins again on Sunday, Mr. Erdogan seemed more interested in talking about foreign policy, and showing a statesmanlike manner before the G-20 meeting, than in discussing the election.
With hostility between the United States and Iran roiling the region, for instance, he warned that the Trump administration’s hard-line toward Iran was a problem for Turkey and other countries that rely on Iranian oil. “How can I ensure heating for my citizens in wintertime?” he said.
Tensions between the United States and Turkey have also risen after Turkey’s purchase of the S-400 missile system, Russia’s most advanced antiaircraft weaponry. The purchase would set off mandatory United States sanctions against Turkey, and it could create another slide in the value of the Turkish lira.
Mr. Erdogan said the missile system would arrive in Turkey in the first half of July, that 100 technicians had already been trained, and that the sites for the weapon’s deployment had been selected. Yet he seemed confident that his apparent rapport with Mr. Trump should be enough to ease the disagreement — and possibly avoid sanctions.
“They should think deeply, because losing a country like Turkey will not be easy,” Mr. Erdogan said of the United States. “If we are friends, if we are strategic partners, then we should handle this issue between each other.”
“I don’t think at all that the sanctions will happen,” he added.
Mr. Erdogan acquired sweeping new powers last summer when the country switched to a presidential system, and in recent years he has shown no hesitation to rule in an authoritarian style. He remains Turkey’s most popular politician by far, but recent polling in Istanbul has been one of several signs that the electorate is growing weary of the dominance of Mr. Erdogan and his party.
During the briefing, he emphatically endorsed his government’s candidate, Binali Yildirim, a former prime minister and close ally, in the mayor’s race. And he criticized the opposition candidate, Ekrem Imamoglu, without once naming him, rejecting his allegations that the previous municipal administration was guilty of waste and overspending.
Mr. Imamoglu spent 17 days as mayor before the election was overturned in light of complaints from Mr. Erdogan’s party, the A.K.P.
Mr. Erdogan dismissed opinion polls that show Mr. Imamoglu leading in the race and said he was confident Mr. Yildirim, a more experienced candidate, would win. But he also said that he would accept the results this time.
The loss of Istanbul would be a personal blow to Mr. Erdogan — he grew up in a working-class neighborhood on the Golden Horn, and the city has been both his home base and the center of his political power and prestige. It would also be a politically devastating loss, as much of his party’s financial resources come from supporters who have profited from municipal contracts in Istanbul, Turkey’s largest city and financial hub.
In discussing foreign policy, Mr. Erdogan talked at length about how the war in Syria continued to drive a need to engage with Russia, in part to manage the fallout from the war and prevent millions more refugees fleeing into Turkey and Europe.
“If we had not done the agreement on Idlib what would have been the outcome?” he asked. And he expressed disappointment that Mr. Trump had not been able to follow through with his promise for a safe zone in northern Syria.
In the briefing, his tone was far more conciliatory than his public speeches, which are often full of fiery rhetoric aimed at his domestic constituency, and he repeatedly voiced confidence that he could overcome disagreements.
“In international diplomacy, to cancel agreements with changes in power, threaten the continuity in relations,” he said of Mr. Trump’s cancellation of the nuclear deal with Iran. “That’s why we should overcome this.”
He expressed deep emotion over the death of Egypt’s former president, Mohamed Morsi, who he said was left to die unattended on the courtroom floor. And he called for international justice to be brought against Saudi officials responsible for the killing of the Washington Post columnist Jamal Khashoggi.
He complained that Saudi Arabia was not prosecuting its own officials despite promising to and was putting pressure on Turkey to stop delving into the case.
“Right now we are receiving messages from the side of Saudi Arabia: ‘Do not escalate this issue too much, this is harming our relations,’ ” he said.