Special counsel Robert Mueller's investigation into Russian election interference has passed the six-month mark, and President Trump's staff is painting a picture of a process nearing its end.

"We still expect this to conclude soon," White House spokeswoman Sarah Huckabee Sanders has told reporters.

Ty Cobb, the outside attorney brought in to help the White House in its response to the probe, told NPR's Tamara Keith that Mueller's interviews with Trump campaign officials would be completed "ideally by Thanksgiving."

In a more recent interview with The Washington Post, he adjusted that estimate, but still said he "remains optimistic that it will wrap up by the end of the year, if not shortly thereafter."

Legal experts and others within the White House, however, are expecting a much longer slog.

"I was Ty Cobb's former law partner, and I think he's a good lawyer, but he's predicted this investigation is going to be over by the holidays, and I don't think there is any way, shape or form in which that's going to happen," said former acting Solicitor General Neal Katyal.

He's a partner at Hogan Lovells, where Cobb worked before joining Trump's team.

"At the end of the day, we don't know a lot. But what we do know is that the investigation looks big and it encompasses a lot of people, and virtually every day there's a new Russian who is popping up connected to the Trump campaign," Katyal said.

Sam Buell, a law professor at Duke University, said he would be surprised if the investigation wrapped up before next November's midterm elections. He thinks the team of lawyers at the White House knows that, too.

"Those lawyers — they're quite experienced with federal investigations. They've been around this stuff, and they know how long it takes," he said.

In Washington, there is a political subtext to nearly everything, and Buell said that might be no different in terms of the way the White House has set expectations for how quickly Mueller's team works.

"One wonders whether it's designed to begin to sort of create a mounting pressure on Mueller next year, of people saying, 'Well what's he doing?' Why is he going on and on with this? Why are they spending all these resources without having produced anything yet?' " he said.

Buell said it could play off the "perhaps unrealistic" public expectations that a massive investigation like Mueller's is perceived the same way the way as a homicide investigation, where "you're just supposed to go to the crime scene and pick up the evidence and take it to court."

"You could try to create that kind of narrative," he said.

Heading into the "long winter" in Washington, here's a look at some of Mueller's potential next high-profile targets, a few of whom are testifying before Congress this week, and the recent developments related to each:

Michael Flynn

All signs suggest an inflection point could be coming soon for Flynn. Lawyers for the former national security adviser have cut off contact with President Trump's legal team — an indication that he could be cooperating with prosecutors or working toward a deal, a development first reported last week by The New York Times.

A number of interactions have come to light that have highlighted Flynn's vulnerability since he was fired by Trump in February. Most recently, it's a June 2015 trip to Egypt and Israel that congressional Democrats say he failed to disclose in applying to renew his security clearance. He's also failed to disclose payments from Russia-linked entities, and gotten into trouble for discussing sanctions with the former Russia ambassador Sergey Kislyak.

Flynn also registered late under the Foreign Agents Registration Act, which normally isn't a problem, but can become one if public reports contradict or show discrepancies in the forms he filed detailing his work on behalf of foreign entities.

Erik Prince

Prince, the former head of the security contractor Blackwater, has come under scrutiny for a meeting earlier this year billed as "an apparent effort to establish a back-channel line of communication between Moscow and President-elect Donald Trump," as reported by The Washington Post.

Prince is scheduled to privately testify on Thursday before the House Intelligence Committee about Russian election interference, although the transcript of the interview is expected to be shared afterward.

While he told the Washington Examiner in October that Mueller has not contacted him, what he tells congressional investigators is sure to be of interest in the special counsel's Russia probe.

Prince made large financial contributions in support of Trump and is the brother of Trump's education secretary, Betsy DeVos, although he had no official role within the Trump campaign or transition team. According to The Post however, he presented himself as "an unofficial envoy" for Trump in setting up a meeting with a confidant of Russian President Vladimir Putin around Jan. 11.

The Trump White House has denied knowing about any such meetings, and at the time, then-press secretary Sean Spicer said, "Erik Prince had no role in the transition."

Jared Kushner

Kushner's responsibilities within the White House may be on the decline, but investigators' interest in the president's son-in-law and senior adviser continues to grow.

On Nov. 16, the Senate Judiciary Committee, which is conducting its own investigation into Russian election interference and possible obstruction of justice, sent Kushner's lawyer a letter complaining that his production of documents "appears to have been incomplete."

Specifically, the letter mentions "emails concerning contacts with WikiLieaks and a Russian backdoor overture" that Kushner did not disclose, despite the documents being "known to exist," reported NPR's Scott Neuman.

A recent story in the New York Times says Kushner had been initially relieved when Mueller was appointed, assuming the special counsel's investigation would halt the parallel probes happening in Congress. That hasn't transpired.

"To some, that suggested he did not get it, that he did not fully grasp how the special counsel would scrutinize every single thing he had done in business, during the transition and during the campaign," wrote The Times' Sharon LaFraniere, Maggie Haberman, and Peter Baker.

Jeff Sessions

Critics said the attorney general appeared to shift his story again in his most recent visit to Capitol Hill this month. Sessions says he has always answered all questions from Congress faithfully.

In his testimony before the House Judiciary Committee, Sessions said news reports helped him recall a March 2016 meeting with foreign policy adviser George Papadopoulos at which Papadopoulos mentioned his contacts with Moscow and the offer of a meeting between Trump and Putin.

That seemed to contradict Sessions' earlier testimony before the Senate Judiciary Committee, where he said he was not aware of any Trump advisers or surrogates that were in communication with Russian officials. Sessions said news reports about the meeting jogged his memory.

In October, Sessions said he had not been interviewed by Mueller's team, but his narrative is sure to be of interest to the special counsel's team if he does end up giving testimony. Sessions is also scheduled to testify before the House Intelligence committee behind closed doors on Thursday.

Donald Trump Jr.

The president's oldest son is at the center of a number of Russia-related interactions, most recently the revelation that he was in contact with WikiLeaks during the 2016 campaign, at the same time the website was publishing damaging emails to the Democratic Party and nominee Hillary Clinton. WikiLeaks acquired the stolen emails via Russian government cyberattacks, the U.S. intelligence community says.

Trump Jr. downplayed his messages with WikiLeaks, but the story continues to further the larger question of how much the Trump campaign knew about Russian interference efforts and whether any campaign officials did anything illegal to help those efforts along. The Senate Judiciary Committee's aforementioned letter to Kushner also seemed to allude to there being more communication between the Trump campaign and WikiLeaks than just the Twitter messages Trump Jr. released.

Mueller is also said to be keenly focused on the 2016 Trump Tower meeting between Trump Jr. and Russian lawyer Natalia Veselnitskaya, among a few others.

Paul Manafort/Rick Gates

Manafort, Trump's former campaign chairman, and his business partner, Gates, are facing charges, but that's far from the end of the story.

Outside legal experts say Mueller might hope to flip Manafort and work out a deal that lessens or eliminates prison time — he's facing the potential of 80 years in prison, according to the Associated Press — in exchange for information about other members of the campaign.

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