Oct 26 (Reuters) - Bible-quoting, tough-talking Shawn Fain on Wednesday scored his first big victory against the Detroit Three through a tentative labor deal with Ford. But the jury is out on whether his aggressive bargaining tactics have soured worker relations with the automakers for a long time.

Six weeks into escalating strikes and heated rhetoric, the United Auto Workers (UAW) president extracted a record 25% wage hike for some 57,000 Ford Motor workers in a tentative deal.

Fain, representing nearly 150,000 auto workers in one of the biggest labor strikes in decades, upended tradition by taking simultaneous action against all three automakers - a bolder, riskier path than his predecessors.

The strike started as the clock hit midnight on Sept. 15, and followed Fain's decision to open negotiations with Ford, General Motors and Stellantis at once, eschewing public niceties involving choreographed handshakes that famously kicked off previous negotiating efforts.

In the past weeks, he ran what amounted to a public auction among the companies, while prior UAW presidents picked just one automaker to set a pattern for the other two.

Wearing T-shirts with slogans like "EAT THE RICH", Fain, 54, announced walkouts at the companies' most profitable factories making SUVs and trucks, pitting them against each other to come up with offers quickly.

"Fain used a series of new tactics for these strikes and negotiations, and the tentative deal at Ford demonstrates how effective those tactics were," said Lynne Vincent, assistant professor in Syracuse University's Whitman School of Management.

"He took the risk of changing the playbook, and it paid off at Ford and may continue to pay off at the other automakers."

Fain was especially tough on Ford, which in the past cultivated a collaborative relationship with the UAW. He said last week: "The days of the UAW and Ford being a team to fight other companies are over. We will always and forever be on the side of working people everywhere."

Fain won office by a narrow margin in a first-ever direct election earlier this year and has sought alliances with high-profile progressive politicians such as U.S. Senator Bernie Sanders to reframe the UAW's contract bargaining as a battle to reset the balance of power between workers and global corporations.

In lengthy social media talks to UAW members, Fain alternates quoting Bible verses with the use of charts and graphs to dissect wage and benefit offers from the automakers - details his predecessors kept behind closed doors during bargaining crunch time.

The strategy is not without risk.

"He won the battle, but whether he wins the war or not, which is to have more union workers getting paid more, is unclear," said Jeffrey Scharf, Chairman of Act Two Investors and a former holder of GM stock.

"That's what I would be more worried about if I was a young auto worker. I would worry about whether this is going to cost me my job in the long-term."

COMPETITIVENESS AND POLITICS

The automakers, along with some analysts and investors, have said the higher costs from any potential deal will hobble their ability to close the gap with electric-vehicle (EV) market leader Tesla and harm workers in the long run.

Fain, however, has rebutted automakers' concerns about labor costs by pointing out that they have poured billions into share buybacks to benefit investors.

"If they've got money for Wall Street they sure as hell have money for the workers making the product," he said.

During negotiations, Fain clashed with Ford CEO Jim Farley and GM chief Mary Barra, citing their million-dollar paychecks as one of the reasons they should be rewarding workers.

The strike has also became a political issue in the 2024 U.S. presidential campaign.

President Joe Biden, facing re-election next year, joined Fain on a picket line outside Detroit on Sept. 26. His chief rival, former President Donald Trump, visited Michigan the next day to woo auto workers' votes with an anti-EV message.

"This tentative agreement provides a record raise to auto workers who have sacrificed so much to ensure our iconic Big Three companies can still lead the world in quality and innovation," Biden said in a statement late on Wednesday.

The UAW has not endorsed Biden's re-election. His administration is pouring billions in federal subsidies into expanding sales of EVs, and a shift to electric threatens UAW jobs at powertrain plants.

The union has criticized the Biden administration for subsidizing battery plants owned by joint ventures of the unionized automakers as they are not bound by contracts and pay lower wages.

Absent from the yet-to-be-ratified contract terms announced on Wednesday was any mention of future pay and unionization at new EV battery factories that Ford is building with an Asian partner.

"I think it's a success with an asterisk. In other words, successful, but with a lot of pain, heartache and damage done to get to this point," Wedbush analyst Dan Ives said.

(Reporting by Joe White and Ben Klayman in Detroit; additional reporting by Eric Cox in Detroit, Bianca Flowers in Chicago, David Shepardson in Washington, Abhirup Roy in San Francisco, Abhijith Ganapavaram in Bengaluru; Editing by Sayantani Ghosh and Devika Syamnath)