Nelson Peltz just received key backing in his high-profile proxy battle against Disney (DIS).

Influential proxy advisory firm Institutional Shareholder Services (ISS) recommended shareholders vote for Peltz of Trian Fund Management to join Disney's board — contradicting the view of another high-profile firm Glass Lewis. The endorsement could breathe new life into Peltz's campaign.

Peltz is currently seeking board seats for himself and former Disney CFO Jay Rasulo.

In a report published Thursday and viewed by Yahoo Finance, ISS said Peltz "as a significant shareholder, could be additive to the succession process, providing assurance to other investors that the board is properly engaged this time around. He could also help evaluate future capital allocation decisions."

"Peltz, with his considerable experience on other boards and fiduciary duties owed to a large shareholding group, appears best positioned to bring a shareholder perspective to the board," the firm added.

Notably, ISS said shareholders should not vote for Rasulo's addition to the board. It also advised shareholders against voting for activist Blackwells Capital's nominees and to withhold their vote against current Disney board member Maria Elena Lagomasino.

Blackwells supports the company's current board but has urged shareholders to vote for its three nominees as additions to it.

On Monday, Glass Lewis recommended shareholders support the company's current board and withhold votes for the nominees put forth by Trian and Blackwells. The firm said CEO Bob Iger's recent initiatives to turn around the business have delivered positive results.

ISS acknowledged these "positive changes," saying it recognizes that "some shareholders may feel that the company has sufficiently course corrected."

"Nonetheless, given the major missteps and severe consequences of the failed 2020 succession, particularly for a company that already had a history of succession drama, it may be difficult for others to simply trust that the board, albeit refreshed, will get it right this time," the firm said.

If the proxy battle continues to a vote, a shareholder meeting set to take place on April 3 will ultimately determine the board's fate.

Last year, Peltz and his hedge fund renewed a push to shake up Disney's board as the stock price hit multiyear lows.

Disney has been grappling with challenges that include a declining linear TV business, slower growth in its parks business, and losses in its streaming business.