(CNN) Amid White House turmoil, a possible government shutdown and falling approval ratings, President Donald Trump's former fixer could be slapped with a lengthy prison sentence Wednesday as part of what the President derides as Robert Mueller's "witch hunt."

Ex-Trump lawyer Michael Cohen is expected to be the first member of Trump's inner circle to receive a significant prison term in connection with special counsel Mueller's investigation into Russian interference in the 2016 election when Cohen is sentenced in federal court.

While Trump has tried to distance himself from Cohen -- accusing him of lying to federal agents to try to earn a lighter sentence -- prosecutors have tied the President even closer to Cohen's crimes, disclosing Friday that Trump had directed Cohen to pay hush money to the two women at the heart of the campaign-finance charges: adult-film star Stormy Daniels and former Playboy model Karen McDougal.

Cohen's sentence, resulting from both the special counsel's investigation and a related case from Manhattan federal prosecutors, will be the most significant marker yet in the overarching Russia investigation, which has encircled Trump and numerous senior officials in his orbit.

Cohen's crimes are bound to reflect on the President despite his protestations, particularly if prosecutors go into even more detail Wednesday on the role that then-candidate Trump played.

The President has repeatedly lambasted Cohen since he first pleaded guilty in August and began meeting with prosecutors. And congressional Republicans have come to Trump's defense, criticizing Cohen and attacking his credibility.

"You mean he can do all of the TERRIBLE, unrelated to Trump, things having to do with fraud, big loans, Taxis, etc., and not serve a long prison term? He makes up stories to get a GREAT & ALREADY reduced deal for himself," the President tweeted last week. "He lied for this outcome and should, in my opinion, serve a full and complete sentence."

Cohen's sentencing underscores the scope and breadth Mueller's probe has taken as it's investigated the ties between Russia and Trump's team, an examination that often has consumed the President for the first half of his term. And it sets the stage for a potential clash with congressional Democrats as they take the House next year, launch their own investigations and consider whether to try to impeach Trump.

Several senior Trump officials have pleaded guilty in the special counsel's investigation, including Trump's former national security adviser Michael Flynn, former campaign chairman Paul Manafort and campaign adviser George Papadopoulos, but none were as close to the President for as long as Cohen.

Trump was asked by Reuters on Tuesday about the number of people in his orbit who had business dealings with Russians before or during his campaign.

"The stuff you're talking about is peanut stuff," he said.

Campaign finance, Trump Tower Moscow

Cohen pleaded guilty in August to two campaign finance violations tied to payments he had made or orchestrated to women during the campaign to stay silent about alleged sexual encounters with Trump, five counts of tax fraud and one count of making false statements to a bank. The Manhattan US attorney's office, which brought those charges, has asked for Cohen to receive a "substantial" sentence of roughly four years.

In that filing, prosecutors acknowledged that Cohen "acted in coordination with and at the direction of" Trump in executing the payments.

Cohen also pleaded guilty last month to a charge from Mueller's office of lying to Congress about how long discussions involving a proposed Trump Tower in Moscow had extended into the 2016 campaign. The special counsel's office did not give a sentence recommendation but said Cohen had cooperated with its inquiries.

Federal prosecutors from both offices are expected to speak in Manhattan federal court on Wednesday before US District Judge William Pauley III, who has a reputation for doling out lengthy sentences in white-collar cases.

Cohen has asked for no prison time, and his lawyers argued in a court filing that he could have "continued to hold the party line, positioning himself perhaps for a pardon or clemency," but instead "he took personal responsibility for his own wrongdoing and contributed, and is prepared to continue to contribute, to an investigation that he views as thoroughly legitimate and vital."

Cohen, his lawyers said, should be commended for his cooperation "in the context of this raw, full-bore attack by the most powerful person in the United States."

In addition to the disclosures from the US Attorney's office in Manhattan about Trump's participation in the payments to silence women, Mueller also supplied fresh revelations on the President in Friday's filings, disclosing new information on a set of efforts to communicate between Trump, his associates and the Russian government.

In one instance, prosecutors said, Cohen told the special counsel he had consulted with Trump about his interest in contacting the Russian government before Cohen suggested in a radio interview in September 2015 that Trump meet with Russian President Vladimir Putin during Putin's visit to New York that fall.

Cohen had previously claimed his comments on air were spontaneous, the court papers said, but he admitted to prosecutors that they came about after his discussion with Trump.

The filings also hinted at various other lines of inquiry, with New York prosecutors noting that "Cohen further declined to meet with the office about other areas of investigative interest" -- matters that may prompt questions from the judge on Wednesday.

Congress split on partisan lines

The disclosures about Trump's role in Cohen's crimes have prompted some key House Democrats, who will take control of the chamber in January, to accuse the President of committing "impeachable offenses."

"Whether they are important enough to justify an impeachment is a different question. But, certainly, they would be impeachable offenses, because even though they were committed before the President became president, they were committed in the service of fraudulently obtaining the office," Democratic Rep. Jerry Nadler of New York, the expected incoming chairman of the House Judiciary Committee, said Sunday on CNN's "State of the Union."

But the newest developments haven't seemed to jeopardize Trump's political standing with Republicans, who in recent days have downplayed the significance of the Cohen court documents and accused the President's former longtime attorney of being a liar.

"We've had prosecutors say things based upon what Cohen said, but then I get back to the fact that Cohen is a liar, so I can't draw any other conclusions," said Senate Judiciary Chairman Chuck Grassley, an Iowa Republican. "I don't draw very many conclusions when somebody lies to Congress."

Trump has continued to deny various aspects of the payments to women who alleged sexual encounters with him, including their illegality. And he has continued to deny the affairs themselves. On Twitter this week, he described the payments as " a simple private transaction ."

Asked over the weekend if he had directed Cohen, his former fixer, to pay the women to stay silent, Trump told reporters: "No, no, no."