The first is conspiracy against the United States for "impeding, impairing, obstructing and defeating the lawful governmental functions of a government agency, namely" the Justice Department and the Treasury Department.
The second is making false statements. According to court documents, Gates lied to the special counsel and the FBI on Feb. 1 about a meeting that took place in March 2013 attended by Manafort, a "senior lobbyist" who is unnamed and a member of Congress who is unnamed.
Gates has acknowledged lying about being told by Manafort that there were no discussions about Ukraine at the meeting.
The guilty plea followed a new indictment from Thursday evening in which prosecutors leveled even more charges against Manafort and Gates than they had been facing before. The two men were accused of laundering millions of dollars from overseas, hiding money from the IRS and other crimes.
Manafort plans to continue fighting the charges.
"Notwithstanding that Rick Gates pled today, I continue to maintain my innocence," he said in a written statement.
Continued Manafort: "I had hoped and expected my business colleague would have had the strength to continue the battle to prove our innocence. For reasons yet to surface he chose to do otherwise. This does not alter my commitment to defend myself against the untrue piled up charges contained in the indictments against me."
Neither Manafort nor Gates has been charged with conspiring with Russia's attack on the 2016 election. Gates' change in plea, however, raises the prospect that Manafort's legal situation also could change again.
Prosecutors could use testimony from Gates to make what would be essentially a case against Manafort for colluding with the 2016 Russian election interference effort, if there is one to be made.
Gates' evidence may increase the likelihood of a conviction on the charges already leveled against Manafort. Gates also could have additional information about Manafort that could result in new charges against him.