SAN FRANCISCO, May 28 (Reuters) - Elon Musk is offering factory tours to 15 Tesla shareholders who vote on his $56 billion pay package at the upcoming meeting, the latest effort by the electric vehicle maker to rally votes for the compensation after a court struck it down.

The upcoming vote is seen as a referendum for Musk's leadership at a time when investors worry that he is distracted by his other ventures and that his often controversial comments are weighing on the reputation and sales of Tesla.

The company is making an unusual and public effort to rally support for the Musk's pay.

"Don't delay, vote today!" Tesla said on Tuesday.

The tour to Tesla's production lines for Cybertrucks and Model Ys in Texas will take place on June 12, the day before Tesla's annual shareholders' meeting, Tesla said on its website.

"Please let us know if you have any questions about voting your Tesla shares!" Musk said on social media platform X, formerly known as Twitter, which he owns.

Musk has threatened to build artificial intelligence products outside of Tesla if he can't get 25% voting power at Tesla, the world's most valuable automaker.

Musk, the world's richest person, currently owns around 13% of Tesla stock, and exercising his stock options would result in him owning a total of 22% of the company.

He has also started AI company xAI, which raised $6 billion in its latest funding.

Tesla has asked shareholders to reaffirm their approval of Musk's record-breaking $56 billion compensation that was set in 2018, but was rejected by a judge who found the package was negotiated by directors who appeared beholden to Musk.

The move came shortly after Musk said Tesla is laying off more than 10% of its global workforce amid falling sales and intensifying competition, especially from Chinese rivals.

Proxy advisory firm Glass Lewis said on Saturday it has urged Tesla shareholders to reject the pay package, citing Musk's "slate of extraordinarily time-consuming projects."

According to data and research firm S&P Global Market Intelligence, 44% of Tesla's common stock is held by nonprofessional shareholders that include retail investors.

That is the most of any of the 10 largest companies including Apple and Nvidia in the S&P 500 by market capitalization. (Reporting by Hyunjoo Jin Editing by Bill Berkrot)