Mr. Han said pathways to a breakthrough remained. Sweden could do more to meet Turkey’s demands, he said, or the United States and other NATO members could throw in “sweeteners” such as arms or economic agreements for the Turks. A thaw in the chilly relationship between Mr. Erdogan and Mr. Biden would also help; the American president has not welcomed Mr. Erdogan in the White House, unlike his three predecessors.
“Turkey either wants to have strong sympathies and actions for its own security concerns or wants to strike a grand bargain with Berlin, Brussels and Washington on issues pertaining to larger foreign and security policy agendas,” Mr. Han said.
The Biden administration has pushed hard for NATO expansion. Turkey wants to buy $20 billion worth of F-16 fighter jets and other equipment from the United States, but administration officials have rejected the idea that Mr. Biden would use this to pressure Mr. Erdogan on NATO expansion.
Mr. Biden mentioned Sweden and the weapons deal together when telling reporters last month about his call with Mr. Erdogan to congratulate him on his re-election.
“He still wants to work on something on the F-16s,” Mr. Biden said of Mr. Erdogan. “I told him we wanted a deal with Sweden, so let’s get that done.”
But congressional resistance to the plan is hardening. Senator Mitch McConnell, Republican of Kentucky and the minority leader, added his voice on Thursday to a growing chorus of influential members of Congress declaring their opposition to sending F-16s to Turkey, calling the idea anathema “until the admission of Sweden gets behind us.”
Mr. McConnell’s resistance, which he discussed in an interview with Punchbowl News, strengthens a blockade being spearheaded by Senator Robert Menendez, Democrat of New Jersey and chairman of the Foreign Relations Committee, who has repeatedly promised to object to the sale unless Turkey becomes “less belligerent” toward its NATO allies.
Absent the State Department’s making an emergency declaration, the Biden administration cannot move forward with the F-16 sale until top Democrats and Republicans on the House and Senate foreign affairs panels acquiesce to it, at a minimum.
Safak Timur and Karoun Demirjian contributed reporting.