Friday is the deadline for the FBI and Justice Department to give the Senate Judiciary Committee key documents in the Michael Flynn case.

It won't happen, because that's not how the current FBI and Justice Department deal with congressional demands involving the Trump-Russia affair. But sooner or later, Judiciary Chairman Sen. Chuck Grassley, R-Iowa, is likely to get his way.

In a May 11 letter to Deputy Attorney General Rod Rosenstein and FBI Director Christopher Wray, Grassley noted that more than a year ago, on Feb. 15, 2017, the Judiciary Committee requested a copy of the transcript of a Dec. 2016 phone call between Flynn and Russian ambassador Sergey Kislyak. It was that call that led the FBI to go to the White House to question the newly installed national security adviser on Jan. 24, 2017, just four days into the Trump administration. And it was that questioning that led to Flynn pleading guilty to lying to the FBI.

The Judiciary Committee request was bipartisan. But the Justice Department refused to hand over the document. Instead, then-FBI Director James Comey briefed the committee on Flynn and other issues on March 15, 2017.

"Director Comey specifically told us during that briefing that the FBI agents who interviewed Lt. General Michael Flynn ' saw nothing that led them to believe [he was] lying,'" Grassley wrote. Comey "led us to believe … that the Justice Department was unlikely to prosecute [Flynn] for false statements made in that interview."

On Dec. 1, 2017, with special counsel Robert Mueller in charge of the case, Flynn pleaded guilty to one count of lying to the FBI.

Now, with Flynn awaiting sentencing, Grassley wants the information he asked for more than a year ago. Plus, he wants the FBI agents' contemporaneous report on the interview, known as a 302, and any other notes or documents relating to the interview (the interview was not recorded.)

It seems certain that the Justice Department, in conjunction with Mueller's office, will refuse, citing an ongoing investigation. That will be true until Flynn is sentenced, or until his case concludes in some other way.

There is no way to predict when that will happen. But tea-leaf-readers watching the Flynn case have noticed one small development that might be a hint things are wrapping up.

On Jan. 31, 2018, Flynn and Mueller jointly asked the court to put off sentencing. "Due to the status of the special counsel's investigation, the parties do not believe that this matter is ready for a sentencing hearing at this time," they wrote. They asked for and received a 90-day extension, until May 1.

Then, on May 1, the parties again declared themselves unready for sentencing. But this time they asked for a 60-day delay, until no later than June 29. It also was granted.

Does the request for a 60-day extension, rather than another 90-day extension, mean the Flynn case is nearing conclusion? The people who know are refusing to talk. But it could be a clue.

One last thing. At the end of his letter, Grassley asked the FBI to "make Special Agent Joe Pientka available for a transcribed interview with committee staff." Pientka is thought to be one of the two agents (with Peter Strzok) who interviewed Flynn on Jan. 24, 2017, and who Comey said did not believe Flynn was lying. Pientka's account of the Flynn interview would be critical to understanding the case — and in terms of public credibility, Pientka would not have the baggage of Strzok, whose text exchanges with fellow FBI agent Lisa Page are under investigation both inside the Justice Department and on Capitol Hill.

If past patterns hold, the FBI will deny the Pientka request, too.

But at some point, perhaps not too long from now, the Flynn case will end. And then, the Justice Department's, and Mueller's, " ongoing investigation" reason for withholding information will no longer apply. No doubt they will try to find another reason to keep the information from Congress. But in the end, Congress, in the person of Grassley, will probably win.