A large agency consulting firm is urging Tesla shareholders to veto CEO Elon Musk's proposed $56 billion compensation packagecrashtestlauncherThis dealt a blow to Tesla's board of directors.

Glass Lewis & Co. The recommendation was made in a report released Saturday, citing the "oversize" of the compensation package and a "diluting effect" when exercised.

"Before the 2018 award, Musk's series of time-consuming projects unrelated to the company were well known, and this situation worsened with his high-profile acquisition of what is now Company X," the report said.

The recommendation could affect the votes of large institutional investors at Tesla's June 13 annual shareholder meeting. If the proposal is rejected, the CEO may follow through on threats to develop products other than Tesla.

Next month's vote will be the second time that Musk's salary plan has been submitted to shareholders for review. The compensation plan was originally formulated in 2018, but earlier this year, a Delaware judge declared it invalid, saying investors had not fully understood key details. If Tesla's board can prove that the compensation package still enjoys widespread support, it could help bring a legal appeal against the ruling. Failure, on the other hand, would be a major embarrassment and a sign that investors are losing trust in Musk's leadership. The vote is only advisory, which means Tesla can choose to ignore it.

About three-quarters of investors supported Musk's compensation plan six years ago. Glass Lewis advised them to veto the plan, citing the high cost and diluting other shareholders.

Tesla has been trying to respond to public criticism of Musk's pay through a campaign to win shareholder support. Board Chairman Robin Denham is reaching out to large institutional investors, while a "Vote for Tesla" website is wooing the support of the company's large retail shareholders.

Separately, Tesla is asking shareholders to vote next month on a proposal to move the company's charter from Delaware to Texas. Glass Lewis recommended voting against the move, as well as voting against the re-election of Elon Musk's brother Kimbal Musk on the board.