WASHINGTON – Paul Manafort, the longtime political operative who helped guide Donald Trump to the White House, will find out Thursday how many of his twilight years will be spent in federal prison.

Prosecutors say Manafort should be locked up for as long as two decades after masterminding a "sophisticated" scheme to defraud American banks and taxpayers out of millions of dollars he amassed through years of illicit lobbying work on behalf of a pro-Russian political faction in Ukraine.

"It is Manafort's own criminal actions that have led to these consequences," they wrote in a court filing this week.

Manafort's lawyers say he deserves leniency. They describe him as an elderly man who has shown remorse for his crimes and is unlikely to commit them again, and they portray him not as a criminal mastermind but as someone ensnared in special counsel Robert Mueller's sprawling investigation into Russia’s interference in the 2016 presidential election and possible cooperation with the Trump campaign.

Those competing portraits will collide when Manafort is sentenced Thursday afternoon in federal court in Alexandria, Virginia.

A jury there convicted Trump's former campaign chairman of eight charges, including bank and tax fraud, related to his work as a political consultant in Ukraine. Federal sentencing guidelines call for him to spend 20 to 24 years in prison, though U.S. District Judge T.S. Ellis could impose a sentence higher or lower than that recommendation.

Whatever Ellis decides will be only the beginning for Manafort. He's scheduled to be sentenced again next week in a federal court in Washington, where he pleaded guilty in a related case and faces as much as an additional decade in prison.

The combination could amount to a life sentence for Manafort, who turns 70 in less than a month.

Any prison sentence would cap off a remarkable fall from grace by the longtime political operative who worked on the campaigns of four Republican presidents, including Trump. He is one of a half-dozen of Trump's top aides and advisers to face charges in a special counsel investigation that cast a cloud over the president's first two years in office and could place him in political jeopardy.

Prosecutors have portrayed Manafort as someone who, despite an already privileged life, lived extravagantly at the expense of American institutions and taxpayers. They argued in court filings that Manafort is likely to re-offend, citing the longevity of his crimes that continued as recently as late last year, when prosecutors said he lied repeatedly despite a plea deal in a separate case in Washington. Among the things for which he was convicted in that case was attempting to obstruct justice while he was on house arrest.

"Manafort acted for more than a decade as if he were above the law, and deprived the federal government and various financial institutions of millions of dollars," prosecutors wrote in one court filing. "The sentence here should reflect the seriousness of these crimes, and serve to both deter Manafort and others from engaging in such conduct."

Prosecutors said Manafort did not report millions of dollars of income from his extensive consulting work for Ukraine's former pro-Russia regime and hid sizable coffers in foreign banks. The crimes predate his time leading Trump's campaign.

Defense attorneys argued in their own sentencing memorandum that Mueller's team has tried to vilify Manafort as a "lifelong and irredeemable felon." They acknowledged that Manafort failed to report income from his consulting work, did not disclose his foreign accounts and provided false information to American banks, but they argued that he did not intend to harm the financial institutions.

"The charges and associated publicity have brought intense, negative media coverage and scrutiny, have destroyed his career, and have resulted in financial hardship for Mr. Manafort and his family," his attorneys wrote, adding that Manafort has already been held in solitary confinement for nine months and has agreed to forfeit a lifetime of assets.

In a response filed Tuesday, prosecutors argued that Manafort has not shown remorse, one of the factors judges typically look at when deciding on a sentence. Instead, prosecutors said, Manafort has blamed "everyone from the Special Counsel's office to his Ukrainian clients" for his crimes, from which he had profited handsomely.

Letters from friends and relatives describe Manafort as a loyal ally and a dedicated family man who once turned down a private dinner with George H.W. Bush, then vice president, to attend his daughter's girl scout graduation.

Bart Mazzarella said the Manafort he had read about in the media is not the man he has known since they were 12.

"I thought to myself, 'How could he possible have committed these crimes?' ... Knowing his life, his family, I've gone to church with him, prayed with him – this could not be the same Paul Manafort. ... He's not the way they say he is," Mazzarella said.

Manafort will face a second sentencing next Wednesday in Washington, where he faces up to 10 years in prison after pleading guilty to conspiracy charges for failing to report his lobbying work in Ukraine and tampering with witnesses to get them to change their stories. His attorneys have asked for a sentence "significantly below" that and have argued that if he's sent to prison in the Virginia case, his term in Washington should run at the same time.

Contributing: Bart Jansen and Kevin Johnson

More on Paul Manafort's legal troubles:

Paul Manafort's lawyers say long prison term would 'likely amount to a life sentence' for Trump aide

Yes, the Mueller investigation is costly. But the millions seized from Manafort have it on track to break even

'His criminal actions were bold': Prosecutors urge harsh sentence for Paul Manafort in court memo

Mueller's office seeks prison sentence of 20 years or more for ex-Trump campaign chairman Paul Manafort