By Elizabeth Dilts

NEW YORK, Nov 9 (Reuters) - Republican Donald Trump's victory in the U.S. presidential race puts a new rule on retirement advice in limbo, even after Wall Street's biggest wealth management firms have spent millions preparing for it, lawyers and analysts said on Wednesday.

The U.S. Department of Labor fiduciary rule, which is set to start taking effect in April, is meant to promote the best interests of retirement savers by eliminating conflicts of interest for brokers.

The financial services industry has tried to stop the rule in the courts, arguing that the Labor Department overreached and that the rule would result in high costs that will ultimately make small accounts unprofitable.

But a federal judge blocked one such lawsuit, and companies like Bank of America Corp's Merrill Lynch and Morgan Stanley have already announced plans to cooperate with the rule.

It could cost firms as much as $31 billion over the next decade to comply, according to Labor Department estimates.

On the campaign trail, Trump has said that "70 percent of regulations can go," and an adviser, Anthony Scaramucci, told Reuters the fiduciary rule "would likely be stopped."

The Trump campaign did not immediately respond to a Reuters' request for comment on his plans for the rule.

A Trump presidency, coupled with Republican control of the U.S. Senate and House of Representatives, have created uncertainty around a whole host of post-2008-2009 financial crisis measures, including the Dodd-Frank reform legisation.

"They will do whatever they want to do," said attorney Jay Gould, who co-chairs the financial services practice at Winston & Strawn LLP. "Say goodbye to Dodd-Frank. Say goodbye to the fiduciary rule at DOL."

Congress and the White House can influence the rule in several ways, including by delaying the April start date with a request for another impact assessment, said Sean Tuffy, head of regulatory intelligence for Brown Brothers Harriman.

"That's a typical trick to use to delay changes to be made," Tuffy said. "This puts the DOL rule in a state of limbo."

However, it will be hard for any politician to block a rule that has such moral appeal, said Michael Spellacy, PwC's head of global wealth management.

"We don't expect any material or significant changes because the core of the rule is about consumer protection, about the elimination of conflicts and about transparency," Spellacy said. "It's a difficult stretch of the imagination to think that Congress would cancel the rule." (Reporting By Elizabeth Dilts; Additional reporting by Suzanne Barlyn, Sarah Lynch, David Henry; Editing by Jonathan Oatis)