Gates appeared at U.S. District Court in Washington on Friday to make the plea, one day after Mueller added new charges against him and Paul Manafort, a business associate and Trump's former campaign chairman.
Manafort has been accused by the team investigating Russian meddling in the 2016 USA presidential elections and possible collusion with the Trump campaign of money laundering, tax fraud and banking fraud for work he did for Yanukovych in 2006-2014.
We have an update now on special counsel Robert Mueller's Russian Federation investigation. "Mr. Manafort is confident that he will be acquitted and violations of his constitutional rights will be remedied".
The charges against the Trump affiliates arise from their foreign lobbying and efforts that prosecutors say they made to hide their income by disguising it as loans from offshore companies.
Prosecutors also said Manafort and Gates obtained more than $20 million in loans by lying about their business income and debts.
Gates and Manafort were charged in October with money laundering and failing to register foreign lobbying work with the USA government.
According to the charges, the pair also did not report their ownership of the foreign bank accounts to US tax preparers.More news: UEFA Europa League: Arsenal To Miss Mesut Ozil, Aaron Ramsey Against Ostersunds
It alleges that Gates paid for personal expenses, his children's tuition and interior decorating with the money from the offshore accounts.
"It enhances the pressure each of them should feel to work out a plea and cooperation agreement".
Paul Manafort says in a statement that the plea by Rick Gates today does not change his commitment to defend himself against what he calls "untrue piled up charges". It did not say which defendant objected.
Gates's lawyers had previously asked a federal judge in Washington for permission to withdraw from the criminal case there, citing "irreconcilable differences".
Gates's lawyer, Thomas Green, declined to comment, saying he would "keep our powder dry".
Gates told investigators on February 1 that Manafort told him that nobody brought up Ukraine at the meeting. Manafort served as President Donald Trump's campaign chairman from June to August 2016. It was the second round of charges against the two men.
Trump's former national security adviser, a retired general who had led the Defense Intelligence Agency, was the first White House official charged in Mueller's probe. Neither man has been sentenced.
Manafort initially focused on the GOP primary race for delegates and then rose quickly to become the Trump campaign manager in May 2016. His team has expressed interest in interviewing the president.