By Stephanie Kelly, Suzanne McGee and Hannah Lang

NASHVILLE (Reuters) - Republican nominee and former U.S. President Donald Trump once blasted cryptocurrency, calling it a "scam." Now, he is headlining one of the industry's biggest conferences.

Trump, who made the comment in 2021, will speak on Saturday, the last day of the three-day Bitcoin 2024 convention in Nashville. Republican former candidate Vivek Ramaswamy, Senator Bill Hagerty of Tennessee and Senator Cynthia Lummis of Wyoming will also speak.

Among Democrats, U.S. Representative Ro Khanna of California is on the roster.

The industry has quickly rebounded after FTX and a series of other crypto companies collapsed in 2022, sending token prices sliding and forcing multiple companies into bankruptcy. Digital asset proponents say that cryptocurrency users are becoming a growing political force this election cycle, although it is unclear just how many users would prioritize crypto over other issues at the ballot box.

The Republican Party is courting their votes by promising lighter regulation, potentially tying a currency built to circumvent government to a major U.S. political party.

"For most of its history, crypto was really a nonpartisan issue," said David Yermack, a professor at New York University's Stern School of Business, because Republicans and Democrats alike did not understand it or care to learn more.

"I do think the Republicans in the last year or two have begun to move a little more quickly in the area."

Stand With Crypto, a nonprofit industry group backed by crypto exchange Coinbase, has organized over 1.3 million advocates. Meanwhile, three major pro-crypto super political action committees - Fairshake, Defend American Jobs, and Protect Progress, all of which did not exist until this cycle - have raised over $230 million to support friendly candidates.

That influence is already being felt. Fairshake, a super PAC promoting pro-crypto candidates, has spent over $10 million this year against California progressive Democrat Katie Porter, who was running for the Senate. Porter, who questioned bitcoin mining's effect on climate change, lost her primary.

Some crypto advocates are backing Trump, including the billionaire Winklevoss twins who founded crypto company Gemini. Each gave him $1 million in bitcoin but had to take back the money because it exceeded the maximum allowed under federal law.

Overall, 7% of U.S. adults held or used crypto in 2023, down 3 percentage points from 2022 and down 5 percentage points from 2021, the Federal Reserve reported in May. But the annual convention is pulling in more politicians than ever.

"There's a joke going around that the list of speakers looks like the RNC Lite," one attendee said in an interview, referring to the Republican National Convention in Milwaukee in mid-July.

TRUMP'S NEW EMBRACE

Trump's appearance at Bitcoin 2024 is his latest show of support for the industry. In a June fundraiser in San Francisco, he slammed Democrats' attempts to regulate the sector. He met bitcoin mining companies at his Mar-a-Lago resort last month.

"We have tried to engage with the Biden administration and they have not been receptive unfortunately," said Jayson Browder, head of public policy for Marathon Digital Holdings, who attended the Mar-a-Lago meeting. "And former President Trump has been more than receptive and is now being an active supporter of our industry."

Trump recently indicated he would like to see more bitcoin mining by U.S. firms.

Crypto executives are upset with the Securities and Exchange Commission's enforcement actions under U.S. President Joe Biden.

The White House told Reuters the Biden-Harris administration will continue meeting with stakeholders and working with Congress to develop necessary safeguards to harness the potential benefits and opportunities of crypto-asset innovation.

Harris would likely advance Biden's crypto policies if she wins the presidential election in November.

Neither the Trump nor Harris campaigns immediately commented for this article.

Traders betting on a second Trump presidency are flocking to asset classes likely to get a boost under his administration.

Crypto and bitcoin in particular are "the cleanest and most direct way to play the 'Trump trade' so far," said Cameron Dawson, chief investment officer of NewEdge Wealth.

Conference attendee Hillary Adler, who co-founded operating system BitcoinOS, has previously voted Democratic but now describes herself as left-libertarian. Calling herself an undecided voter, Adler said she is not surprised that some Republican politicians have pivoted to supporting crypto.

"The Republicans have always had better long-tail strategies, politically," she said. "Now, they care about crypto."

(Reporting by Stephanie Kelly in Nashville, Suzanne McGee and Hannah Lang in New York; Editing by Heather Timmons and Richard Chang)