The cryptocurrency industry is mourning the loss of its fiercest advocate on Capitol Hill after Sen. Cynthia Lummis announced Friday she would not seek reelection. 

Lummis, R-Wyo., said last week that the "difficult, exhausting" final weeks of this year's Congress led her to withdraw her reelection bid, saying she's "come to accept that I do not have six more years in me."

Lummis is chair of the Senate Banking Committee's crypto subpanel and a reliable ally for the industry — helping muscle through the Genius Act, a first-of-its-kind bill regulating stablecoins, in July. She is currently negotiating legislation as part of an industry-backed push for broader regulation of cryptocurrency. 

Crypto interests bemoaned her retirement, which sets up a primary for her seat in ruby-red Wyoming in 2026. 

"Senator Lummis has been a great ally on crypto — very sorry to see her go!" said David Sacks, the White House AI and crypto czar, in a post to X. 

Conner Brown, the head of strategy and the Bitcoin Policy Institute, called Lummis "the Senate's first and finest bitcoiner."

"We are incredibly lucky to have had her leadership at so many critical moments for bitcoin policy over these critical years," Brown said. 

And Coinbase vice president of U.S. policy Kara Calvert said Lummis has "helped bring digital assets from the fringes of policy debates to the floor of the U.S. Senate."

"I can think of no better way to cap off her legacy than passing the landmark market structure legislation she's fought so hard to advance," Calvert said.

Lummis was first elected to the U.S. House of Representatives in 2008, where she served until 2016. She was elected to the Senate in 2020, becoming the first female senator from Wyoming. 

Republican Rep. Harriet Hageman is Wyoming's lone representative in the House. People familiar with her thinking told NBC News she is likely to run for Lummis' seat. 

Whoever wins a Republican primary for the seat is highly favored to win the general election. President Donald Trump carried Wyoming by more than 45 points in the 2024 election. 

Hageman defeated then-Rep. Liz Cheney, R-Wyo., in 2022. Cheney lost Trump's favor after she voted to impeach him in the wake of the Jan. 6 attack on the Capitol and joined Democrats in investigating his conduct that day. 

Hageman lauded Lummis for her work on crypto in a statement, saying Lummis' "forward-looking approach reflects her belief that financial and technological progress can coexist and allow for individual freedom and fiscal safety." 

— CNBC's Emily Wilkins contributed to this report.