Former Trump campaign chairman Paul Manafort has agreed to co-operate with an investigation into alleged Russian meddling in the US election as part of a plea deal.
In court on Friday, he pleaded guilty to two criminal charges in the deal with Special Counsel Robert Mueller.
The agreement avoids a second trial on money laundering and other charges.
The White House insists the guilty plea has absolutely nothing to do with President Donald Trump.
Manafort was convicted last month on eight counts of fraud, bank fraud and failing to disclose bank accounts.
That was the first criminal trial arising from the justice department's investigation into alleged interference by Russia in the 2016 election.
However, the charges only relate to Manafort's political consulting with pro-Russian politicians in Ukraine, largely pre-dating his role with the Trump campaign.
What happened on Friday?
In an appearance at a federal court in Washington DC, Manafort - who is being held in custody - pleaded guilty to one charge of conspiracy against the US and one charge of conspiracy to obstruct justice.
Correspondents say he faces up to 10 years in prison under the deal and will also forfeit four of his properties and the contents of several bank accounts. Deadlocked charges from the previous trial will be dismissed if there is "successful co-operation" with the special counsel.
A lawyer for Manafort, Kevin Downing, told reporters outside the court that his client "wanted to make sure that his family was able to remain safe and live a good life".
Manafort, 69, worked for Mr Trump's presidential campaign for five months in 2016 and was in charge when Mr Trump clinched the Republican party nomination.
In a statement, White House spokeswoman Sarah Sanders said on Friday: "This had absolutely nothing to do with the president or his victorious 2016 presidential campaign. It is totally unrelated."
President Trump has branded the Mueller investigation a "witch hunt" and insisted there was no collusion between his team and Russia. The Kremlin has also repeatedly denied any meddling.
The charges in the planned second trial were to include money laundering, conspiring to defraud the US, witness tampering and failing to register as a foreign agent. Jury selection had been due to start on Monday.
What might Manafort reveal?
Analysis by Anthony Zurcher, BBC News, Washington
In a year filled with blockbuster Friday news stories, the announcement that Paul Manafort is co-operating with Robert Mueller's investigation is one of the biggest.
Although the White House downplays his importance to the campaign, Mr Manafort had top perch in the Trump team for key months in 2016.
For instance, he was in the June Trump Tower meeting with Donald Trump Jr, Jared Kushner and Russian nationals that was originally billed as a chance to obtain damaging information Russia had on Democratic candidate Hillary Clinton. He took cryptic notes about that meeting that he now might be willing to discuss.
After his August conviction on financial and tax fraud charges in Virginia, the prospect of Mr Manafort's walking away from his legal headaches a free man had been eliminated. It appears that the reality of additional legal expenses and possibly more prison time finally pushed the long-time Washington lobbyist to make a deal. This is probably exactly what the special counsel team had hoped for.
Now the president, who tweeted last month that Mr Manafort was a "brave man" who "refused to break and make up stories in order to get a deal", is left to wonder what comes next.
How did we get here?
Manafort was charged by Mr Mueller last October. At trial, he was accused of using 31 foreign bank accounts in three different countries to evade taxes on millions of dollars.
Prosecutors presented evidence of Manafort's luxurious lifestyle, saying it was only possible because of his bank and tax fraud.
Following last month's conviction, President Trump praised his former campaign chairman for refusing to "break" under legal pressure.
He tweeted he felt "very badly" for Manafort and lauded him for declining to "make up stories" to get a deal.