Legere will be replaced by his top lieutenant, chief operating officer, and president Mike Seivert. Legere will remain a member of T-Mobile’s board of directors.

Legere said he plans to try and complete T-Mobile’s $26.5 billion merger with Sprint before he steps down. “This succession news changes nothing” about the pending Sprint deal, Legere said on a call with reporters and analysts.

“These are big shoes to fill,” Sievert said on the call. “Our best stories and our best days lie ahead.”

Shares of T-Mobile, which have gained 23% so far this year, were down 2% in pre-market trading on Monday.

The announcement comes even as T-Mobile is negotiating with Sprint over reworking their 2018 merger agreement. Legere said the two sides have made progress in their recent talks, but had not reached a final agreement yet. Although the deal has already won approval from federal antitrust regulators, more than a dozen state attorneys general have gone to court to stop the combination.

T-Mobile had said when the deal was announced that Legere would lead the combined company, but at that time, the deal was expected to close much sooner. Legere’s current contract with T-Mobile expires on April 30, 2020.

“It was always expected to be now, but we always expected the new T-Mobile to exist about six months ago… it’s Mike’s time. He’s ready. He’s at the perfect point,” Legere said.

Legere has been rumored a possible candidate to take over the CEO job at troubled real estate startup WeWork. He worked closely on the Sprint deal with current WeWork chairman Marcelo Claure and SoftBank Group chairman and major WeWork investor Masayoshi Son.

But on Monday, Legere denied the rumors. “I was never having discussions to run WeWork,” he said. “But because we had this announcement coming, I couldn’t say that.”

Legere leaves an incredible legacy at T-Mobile, which was hemorrhaging customers after a failed merger with AT&T when he joined in 2012. Since then, the company has attracted more new customers than its three main rivals, AT&T, Verizon, and Sprint, combined. And since going public via a reverse merger with MetroPCS in 2013, T-Mobile has also far outperformed its rivals in the stock market.

Legere also occasionally got into trouble making overly harsh statements on Twitter, where he has 6.5 million followers. In one case, Legere famously got into a Twitter beef with President Donald Trump, a year before before Trump had won the 2016 election. Asked on Monday if he had a desire to get into politics, Legere laughed off the question. “That really worked out well for me in the past,” he responded, laughing. “I’m just going to be a T-Mobile brand fanatic.”

Sievert joined Legere’s team in 2012 as chief marketing officer after a career as a top marketing executive at companies including AT&T and Microsoft. He was promoted to chief operating officer in 2015 and president last year.