President Trump's outside legal counsel is "pleased with the progress being made" in talks with Special Counsel Robert Mueller about a potential interview of the president, a source familiar with the process told Fox News on Thursday.

The source said any interview of Trump is unlikely to take place before the November midterm elections. However, when asked about the odds of Trump answering questions posed by Mueller, the source said: "I think the plane lands."

Earlier this month, Fox News reported that Trump's attorneys had proposed to Mueller that any presidential interview be limited to written questions and answers about allegations of Russian collusion with members of the Trump campaign. The proposal also stated that the Trump legal team would not entertain questions about obstruction of justice.

Mueller has previously asked for the option of an in-person follow-up interview on the collusion issue, which Trump's team is resistant to but has not rejected outright.

Trump has repeatedly stated that he is willing to answer the special counsel's questions, while his legal team -- led by Rudy Giuliani and Jay Sekulow -- has shown more reluctance to allow such an encounter.

The information comes one day after a federal judge set Dec. 18 as the sentencing date for former National Security Adviser Michael Flynn, who has been a key cooperator in the Mueller probe.

Flynn resigned in February 2017 and pleaded guilty that December to lying to the FBI about his contacts with Sergey Kislyak, Russia's ambassador to the U.S., during the transition period between Trump's election and inauguration.

According to his plea , Flynn discussed U.S. sanctions with Kislyak on Trump's behalf during the presidential transition and said members of the president's inner circle were aware of, and in some cases directing, his efforts. Flynn had urged Kislyak not to respond to sanctions imposed by the Obama administration in response to Russian election interference.

Flynn also admitted to lying about Turkish lobbying and research work. He belatedly registered with the Justice Department as a foreign agent for the work weeks after he left the White House.

Flynn and other Trump campaign officials who have pleaded guilty in the Mueller investigation -- including former campaign chairman Paul Manafort and former foreign policy adviser George Papadopoulos -- have not been accused of any crimes related to election interference.

The Associated Press contributed to this report.