A whirlwind week in Special Counsel Robert Mueller's Russian meddling probe is set for a dramatic triple-threaded conclusion Friday, as fired FBI Director James Comey prepares to testify before House Republicans and prosecutors finalize pivotal sentencing documents on former Trump lawyer Michael Cohen and onetime campaign chairman Paul Manafort.

With multiple reports and other indications suggesting the long-running Russia probe that began in May 2017 is nearing its conclusion, Mueller faces court-imposed Friday deadlines to file potentially revealing memos outlining how Manafort allegedly broke his cooperation agreement with the government, as well as how Cohen should be punished for lying to Congress in 2017 about an abandoned Trump real estate project in Moscow.

The planned submissions are set to come just days after Mueller's office submitted a heavily redacted sentencing memorandum indicating that fired national security adviser Michael Flynn had provided "substantial assistance" with several ongoing investigations and recommending no prison time. Trump attorney Rudy Giuliani called Mueller's prosecutors "sick puppies" in the wake of that filing.

Meanwhile, Comey is slated to testify behind closed doors before the House Judiciary Committee, after dropping his longshot legal challenge to congressional Republicans' subpoena earlier this week when they agreed to make public a transcript of his remarks.

Fox News has confirmed that a key focus of questioning will be Comey's decision to write the July 2016 statement recommending against filing criminal charges in the Hillary Clinton email probe before the former secretary of state was even interviewed, as well as the apparent political bias demonstrated in a slew of text messages and leaks by top FBI officials.

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Republicans are also expected to ask about the comparably favorable treatment afforded by the FBI to Clinton advisers. In October, U.S. District Court Judge Royce Lamberth said he was "shocked" and "dumbfounded" when he learned that FBI had granted immunity to former Clinton chief of staff Cheryl Mills during its investigation into the use of Clinton's server, according to a court transcript of his remarks.

House Overight Committee Chairman Trey Gowdy, R-S.C., told host Shannon Bream on "Fox News @ Night" Thursday that Republicans will additionally focus on potential Foreign Intelligence Surveillance Act (FISA) court abuse by the FBI.

On four occasions, the FBI told the FISA court as part of its application to surveil former Trump aide Carter Page that the agency "did not believe" former British spy Christopher Steele was the direct source for a Yahoo News article implicating former Page in Russian collusion.

But London court documents later revealed that Steele -- who worked for a firm hired by the Clinton campaign and Democratic National Committee (DNC) -- was, in fact, the source for the Yahoo News article that the FBI suggested provided an independent basis to monitor Page. Page has not been charged with any wrongdoing despite the lengthy surveillance, and he is now suing the DNC for defamation.

"The FISA abuses and whether or not the world's premier law enforcement agencies should be relying -- even in a in a marijuana case -- on information that you have not vetted corroborated or contradicted" were among the "salient" issues, Gowdy said. "So what is the threshold for the reliability and credibility of the information?"

He added that he wants to ask Comey on Friday whether the agency later tried to corroborate facts in its FISA application to surveil Page.

"The FBI had a criminal investigation into a presidential candidate, and then less than a month after that ended, they launched a counter-intelligence investigation into the campaign of the other major presidential candidate," Gowdy told Bream. "So that's a lot of power that we have given an entity -- it's not too much to ask for the former head of that entity to come explain to Congress the decisions made and not made during the relevant time period."

Trump fired Comey in May 2017, prompting Comey to leak memos documenting statements by the president in which he purportedly demanded Comey's loyalty and suggested Comey curtail the investigation into Flynn.

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The leaked memos led to Mueller's appointment, and fueled Republicans' claims that Comey was unfit to lead the FBI.

The president made clear early Thursday that the pending developments were on his mind, characterizing Mueller's investigation as "Presidential Harassment" that is undermining his poll numbers.

For Manafort, the sentencing document requested by Obama-appointed U.S. District Judge Amy Jackson in Washington, D.C., could be electronically filed at any time on Friday. Mueller's team said in a court filing late last month that Manafort -- who avoided a trial in Jackson's courtroom in September by pleading guilty and vowing to cooperate with prosecutors -- had instead lied to the FBI and Justice Department "on a variety of subject matters."

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Manafort's defense team, which has rejected prosecutors' claims that he violated the terms of the plea agreement, will have two weeks to respond to Mueller's filing on Friday. Jackson could schedule a hearing before she rules on whether to throw out Manafort's plea deal -- which could expose Manafort to further charges. Jackson has set a tentative sentencing date of Mar. 5.

Manafort was convicted on several bank and fraud charges in a separate Virginia federal case in August overseen by Judge T.S. Ellis III. A sentencing date of Feb. 8 has been set in that case.

Manafort could have yet more involvement in other ongoing federal probes. A separate investigation referred to DOJ prosecutors by Mueller earlier this year into possible criminal activity by Clinton-linked Washington insider Tony Podesta and former Obama White House Counsel Greg Craig is reportedly heating up, as prosecutors increasingly reach out to potential witnesses.

Podesta's firm previously did work for Manafort, raising the possibility that the ex-Trump campaign chairman will be involved in yet another potential prosecution. Podesta was offered so-called "use immunity" by Mueller this summer that would have compelled him to testify in Manafort's planned D.C. trial, which did not occur as scheduled because of Manafort's plea deal.

"Use immunity" is a limited form of immunity that only protects Podesta from prosecution based on his own statements on the witness stand. Even if Podesta ultimately provides testimony, he would still be open to potential prosecution based on materials that prosecutors might uncover independently from his testimony.

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Meanwhile, U.S. District Court Judge William Pauley has imposed a 5 p.m. EST deadline for both Mueller and prosecutors in the Southern District of New York to hand-deliver separate sentencing submissions on Cohen, the former Trump attorney and right-hand man who has pleaded guilty in cases handled by both offices.

In the Mueller probe, Cohen pleaded guilty late last month to lying to Congress about a Trump real estate project in Russia. And in August, Cohen pleaded guilty in a separate case that Mueller referred to prosecutors in the Southern District of New York because it fell outside the scope of his congressional mandate to probe possible Russia collusion.

In the August plea, Cohen admitted to violating federal campaign finance laws by arranging hush-money payments to porn star Stormy Daniels and Playboy model Karen McDougal in the weeks leading up to the election “at the direction” of then-candidate Trump.

In all, Cohen pleaded guilty to five counts of tax evasion, one count of making false statements to a financial institution, one count of willfully causing an unlawful corporate contribution, and one count of making an excessive campaign contribution.

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But legal experts were split on the significance of the plea, because campaign finance laws are notoriously murky, and Cohen's plea does not necessarily indicate that prosecutors could have successfully prosecuted a campaign finance case against Cohen or Trump. Cohen was also accused of violating numerous other banking and fraud laws, and could have pleaded guilty to the campaign finance charge to lighten his potential sentence, experts said.

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And a former chairman for the Federal Election Commission (FEC) has said that campaign finance laws are often an unfair lose-lose proposition for candidates, which is why they are often pursued as civil matters, rather than criminal ones.

"Suppose Trump had used campaign funds to pay off these women," former FEC chairman Bradley Smith wrote in The Washington Post. "Does anyone much doubt that many of the same people now after Trump for using corporate funds, and not reporting them as campaign expenditures, would then be claiming that Trump had illegally diverted campaign funds to 'personal use?'"

Trump has played down Cohen's pleas, saying in a series of tweets that campaign finance laws are rarely prosecuted at the criminal level, and are often handled as civil matters -- unless politics gets involved.

"Michael Cohen plead guilty to two counts of campaign finance violations that are not a crime," Trump wrote on Twitter in August. "President Obama had a big campaign finance violation and it was easily settled!"

That was an apparent reference to a nearly $400,000 fine issued in 2013 by the Federal Election Commission against Obama's 2008 presidential campaign for a slew of administrative violations.

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And after Cohen's plea last month, the president swiftly fired back, blasting Cohen as a "weak person," and claiming his former attorney was "lying" to get a reduced sentence. Cohen is set for sentencing the morning of Dec. 12.

Other potential former Trump associates and prominent conservatives seemingly remain in the crosshairs. At a speech at the American Priority Conference in Washington, D.C., GOP operative Roger Stone said he was "proud" to have Trump's public support as he vowed to never testify against the president.

"Few Americans, I think, could withstand the kind of legal proctological examination that I have been under for the last two and a half years," Stone said. "Mr. Mueller and his strike force have examined every aspect of my personal life. My family life. My social life. My business life. My political life. My sex life. FBI agents have been seen rummaging through my garbage. My cleaning lady was interviewed by the Federal Bureau of Investigation.

"Yet I ask this question," he added. "What does any of that have to do with Russia collusion?"

Stone this week invoked his Fifth Amendment right against self-incrimination in refusing to testify and produce documents before the Senate Judiciary Committee in a closed-door setting.

Raising an objection similar in some ways to Comey's concerns about offering testimony before the House Judiciary Committee, Stone said he wanted to avoid a "replay" of the situation in September 2017, when he testified privately before the House Intelligence Committee but remains unable to see a transcript of his own remarks.

"I will not testify unless I am allowed to testify in public so the American people can hear every word," Stone said to applause. He said the Russia probe is focused not on collusion, but on "perjury traps and trumped-up process crimes."

Late Thursday, Trump tweeted a comment on Fox Business Network by former Infowars editor Jerome Corsi, who has alleged that Mueller is attempting to bully him into providing false testimony in the Russia probe.

The president also again derided Mueller's team as "17 Angry Dems," referring to prosecutors in the Special Counsel's office who donated to Democratic candidates.

"He is not alone, Trump wrote. "17 Angry Dems. People forced to lie. Sad!"

Fox News' Bill Mears and Jake Gibson contributed to this report.