(Bloomberg) -- ESG fund managers are being urged to keep their lawyers very close, after Donald Trump emerged as the winner of the US presidential race.

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Trump’s return to the White House threatens to turbo-charge a years-long GOP assault on environmental, social and governance investing strategies. Investors intending to continue with ESG portfolios will need to ensure they understand the intricacies of the US legal system well, according to analysts at Jefferies Financial Group Inc.

“We’d encourage all ESG fund managers to have a lawyer on the team, or on speed-dial,” analysts led by Aniket Shah wrote in a note to clients on Wednesday. “Antitrust risk remains high for asset managers in ESG; there haven’t been any cases yet, thus there is no legal precedent. Further, legal risks regarding fiduciary duty will stay relevant as states enforce anti-ESG laws.”

News of Trump’s win has already battered stocks in green sectors, with shares of wind-energy companies among some of the biggest losers on Wednesday morning. But aside from the threat of bans and obstructive policies, the ESG industry now looks increasingly vulnerable to legal threats.

Key members of the GOP have long alleged that firms embracing ESG are ignoring their fiduciary duties, while Republican attorneys general have alleged that financial firms that incorporate ESG metrics may be guilty of collaborating against the fossil-fuel industry, and fanning inflation.

A likely consequence of the new political landscape will be “greenhushing,” the Jefferies analysts said, referring to the phenomenon of not making public any work on ESG.

Corporate chief executive officers also are likely to consult with their lawyers on how best to navigate the new environment.

“General counsels are in the ear of CEOs, frightened about legal retaliation to ESG initiatives,” the Jefferies analysts said. “The backlash could lead to more focused and pragmatic companies, engaging in strategic discussions closely tied to their business model.”

One counterargument is that any “consumer and employee-led outcry similar to 2016” might push companies to take stances on issues like abortion, as well as diversity and inclusion, according to the analysts.

The situation may be exacerbated by states across the ESG divide pushing diametrically opposed policies. Such a scenario would risk devolving into a “nightmare” of fragmented requirements, the analysts said.