President Donald Trump’s former attorney lied to Congress about his role in pursuing a business deal in Russia for his old boss, covering up that discussions stretched into the 2016 presidential campaign and even reached the Kremlin.

Michael Cohen pleaded guilty in a Manhattan federal courtroom on Thursday to one count of making a false statement to Congress last year when he told lawmakers about his efforts to secure a deal to build a Trump Tower in Moscow. Cohen’s plea was part of a deal he struck with special counsel Robert Mueller’s office that included significant cooperation with the investigation into Trump’s ties to Russia during the presidential campaign.

In an August 2017 letter sent to the House and Senate intelligence committees, Cohen said plans for a Moscow tower had ended shortly before Trump competed in the Republican presidential primaries. “By the end of January 2016, I determined that the proposal was not feasible for a variety of business reasons and should not be pursued further,” Cohen wrote.

But prosecutors say Cohen continued to discuss the proposal throughout the primaries and into the general-election season with Trump’s former business partner, the real-estate developer and convicted felon Felix Sater.

Cohen also told the Senate Intelligence Committee he did not discuss the project extensively within the Trump Organization. In fact, Mueller’s office said, Cohen discussed the project with Trump more than three times and “briefed family members of” Trump about it.

Cohen told Congress that he “never agreed to make a trip to Russia” about the proposal, but emails with Sater show Cohen repeatedly agreeing to Sater’s proposal for a trip to Moscow to seal the deal.

“ASSUMING the trip does happen the question is before or after the convention,” Cohen wrote to Sater in May 2016, two months before the Republican National Convention, adding Trump might potentially go to Moscow and meet Russian President Vladimir Putin around that time.

Cohen also allegedly lied about his communications with Dmitry Peskov, a spokesperson and close adviser to Putin, about the project. Cohen’s letter to Congress said he did “not recall any response to my email, nor any other contacts by me with” Peskov after he emailed him in January 2016 looking for help with the real-estate development plans.

But prosecutors say Cohen followed up with Peskov’s assistant in a phone call and “requested assistance in moving the project forward, both in securing land to build the proposed tower and financing the construction.”

In a court appearance Thursday, Cohen explained his lies by saying he “made these statements” to Congress to be consistent with Trump’s “political messaging” and to be loyal to Trump.”

Just a few weeks after Cohen’s last discussions of the tower project in June 2016, Trump tweeted: “For the record, I have ZERO investments in Russia.”

It was also revealed Thursday that Cohen has entered into a cooperation agreement with Mueller’s office as part of his plea deal. ABC News reports that Cohen sat with members of the office for a combined 70 hours, fielding questions about possible contacts between Russia and the Trump campaign, Trump’s business dealings in Russia, as well as possible obstruction of justice by the president.

Cohen’s cooperation with the Mueller inquiry on potential Russian collusion is significant because it shows that Cohen has been spilling more information to the Mueller investigation than previously known.

In August, Cohen pleaded guilty to tax evasion and bank-fraud charges to Manhattan federal prosecutors as part of an illegal scheme to pay hush money to Trump’s alleged former mistresses, Stormy Daniels and Karen McDougal.

Cohen is scheduled to be sentenced for those crimes on Dec. 12. In exchange for his guilty plea and cooperation with the special counsel’s office, Cohen may hope to receive a lighter sentence than he otherwise would.