WASHINGTON – President Donald Trump’s former campaign chairman, Paul Manafort, pleaded Monday to avoid a lengthy prison term that would "likely amount to a life sentence" for his convictions in the investigation of Russian interference in the 2016 election.

Manafort is scheduled to be sentenced twice next month, first by a federal judge in Virginia where he was convicted of tax and bank fraud; then a week later by another federal judge in Washington, where he pleaded guilty to conspiracy and lying to investigators. Together, those cases could produce what is effectively a life sentence for the 69-year-old political operative.

Prosecutors working for special counsel Robert Mueller have described Manafort as a "hardened" criminal who "brazenly violated the law" through years of fraud and illicit lobbying work. They have urged both judges to order that he serve a significant prison sentence.

Manafort, who pleaded guilty to two conspiracy charges in the District of Columbia, said the harsh descriptions of his crimes weren't for "murder, drug cartels, organized crime, the Madoff Ponzi scheme or the collapse of Enron." And the charges aren't about "collusion" between the Trump campaign and Russia, which was the core of what Mueller's office is investigating, his lawyers argued.

Rather, Manafort pleaded guilty in Washington to crimes related to his lucrative lobbying work in Ukraine, failing to report it to the government and attempting to conceal it from the authorities, his lawyers argued in a 47-page filing late Monday. They said that in the past, the government has prosecuted such cases only rarely, and had not viewed them as particularly serious.

"A lengthy jail sentence is not called for in this case and would not further the statutory goals of sentencing," Manafort's lawyers said. "Mr. Manafort has been punished substantially, including the forfeiture of most of his assets. In light of his age and health concerns, a significant additional period of incarceration will likely amount to a life sentence for a first time offender."

Manafort faces a maximum of 10 years when U.S. District Judge Amy Berman Jackson sentences him March 13.

Manafort's lawyers didn't say exactly what sentence they think would be appropriate, but argued it should be "significantly below" the decade he could face.

That sentence will come after U.S. District Judge T.S. Ellis sentences March 8 in Virginia. Mueller's office said in that case that federal guidelines call for him to spend 20 to 24 years in prison following his conviction on eight counts of bank- and tax-fraud.

Mueller's office said in a court filing on Saturday that it might ask Jackson to serve first one sentence and then the other. But Manafort's lawyers said if a prison term is imposed in Virginia, the D.C. term should run at the same time.

"For over a decade, Manafort repeatedly and brazenly violated the law," prosecutor Andrew Weissmann wrote in a 25-page sentencing memo that was made public on Saturday. "His crimes continued up through the time he was first indicted in October 2017 and remarkably went unabated even after indictment."

The cases stemmed from when Manafort served as a political consultant for a pro-Russian faction in Ukraine during the decade before he joined Trump’s campaign from March to August 2016.

Manafort was a key figure in Mueller's Russia probe because he was a top aide to Trump's campaign who also had extensive connections to Russian interests. Manafort attended a Trump Tower meeting in June 2016 with Russians offering damaging information about Democratic rival Hillary Clinton.

Manafort's partner in the Ukraine work, Russian national Konstantin Kilimnik, also faces conspiracy charges in the D.C. case. Court filings described Manafort meeting more than he acknowledged with Kilimnik during the Trump campaign and sharing polling data.

None of the charges against Manafort involve his work for the campaign.

In August, Manafort was convicted in Virginia of hiding tens of millions of dollars in overseas banks and corporations, to avoid paying taxes. His guilty plea in September in D.C. dealt with conspiracy charges for failing to report lobbying for Ukraine and for tampering with witnesses to get them to change their stories.

Manafort may find it difficult to pay the fines and restitution. He has already forfeited properties worth an estimated $27 million, including a $7.3 million compound in the Hamptons and a $3.8 million apartment in Trump Tower.

More on Paul Manafort's legal troubles:

'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

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