By Jake Coyle, Film Writer

NEW YORK (AP) --

Growing calls for a boycott of the Academy Awards over the lack of diversity among this year's Oscar nominees are forcing stars to choose sides and threatening to throw the movie industry's biggest night of the year into turmoil.

The backlash over the second straight year of all-white acting nominees is also putting heavy pressure on the Academy of Motion Pictures Arts and Sciences to diversify its overwhelmingly white male membership.

The furor grew on Tuesday when the Rev. Al Sharpton said he would lead a campaign encouraging people not to watch the Feb. 28 telecast. On Monday, Spike Lee, this year's Oscar honoree for lifetime achievement, and Jada Pinkett Smith announced they will boycott the ceremony in protest.

Academy president Cheryl Boone Isaacs, who has led efforts to diversify the academy, responded late Monday evening with a forceful statement saying that those previous measures weren't enough.

Isaacs, the academy's first African American president, said that "it's time for big changes" and that she will review membership recruiting to bring about "much-need diversity" in the academy's ranks.

At a Los Angeles gala honoring Boone Isaacs on Monday night, actor David Oyelowo – who was famously snubbed last year for his performance as the Rev. Martin Luther King Jr. in "Selma" – expressed frustration with the academy.

"This institution doesn't reflect its president and it doesn't reflect this room," Oyelowo said. "I am an academy member and it doesn't reflect me and it doesn't reflect this nation."

Other stars began weighing in. George Clooney, in comments to Variety, said that after earlier progress by the industry, "you feel like we're moving in the wrong direction." He noted that movies like "Creed," ''Straight Outta Compton," ''Beasts of No Nation" and "Concussion" may have deserved more attention from the academy.

"But honestly, there should be more opportunity than that," Clooney said. "There should be 20 or 30 or 40 films of the quality that people would consider for the Oscars. By the way, we're talking about African Americans. For Hispanics, it's even worse. We need to get better at this. We used to be better at it."

A 2012 Los Angeles Times study found that the academy was 94 percent white and 77 percent male.

UCLA's latest annual Hollywood Diversity Report concluded that women and minorities are substantially underrepresented in front of and behind the camera, even while audiences show a strong desire for films with diverse casts. Hispanics and African Americans go to the movies more often than whites do.

UCLA surveyed film and TV executives and found that 96 percent are white.

In his comments Monday, Lee said the Oscars' problems ultimately reside with "the gate keepers" who have the power to green-light projects.

Isaacs enlisted Chris Rock, who famously called Hollywood "a white industry" a year ago, as host of this year's ceremony. The backlash all but ensures Rock's opening monologue will, for many, be the most anticipated event of the show.

Last year's broadcast, hosted by Neil Patrick Harris, was also boycotted by some viewers because of the all-white slate of acting nominees. Ratings dipped to a six-year low for ABC.

Some on Tuesday put pressure on Rock to join the boycott. The rapper 50 Cent urged on Instagram: "Chris, please do not do the Oscars awards. You mean a lot man, don't do it." A representative for Rock didn't immediately respond to an email.

One person emphatically not on board with the boycott was actress Janet Hubert, who starred with Will Smith on the '90s sitcom "The Fresh Prince of Bel-Air." In a video posted on Facebook, she lambasted Pinkett Smith for asking actors to jeopardize their career for an insubstantial cause.

"There's a lot of s— going on the world that you all don't seem to recognize," said Hubert. "People are dying. Our boys are being shot left and right. People are starving. People are trying to pay bills. And you're taking about some motherf—— actors and Oscars. It just ain't that deep."

Just how much more Boone Isaacs can do to promote diversity at the academy, where membership is for life, remains to be seen. In November, she launched a five-year initiative to encourage more diversity in Hollywood, called A2020.

But Boone Isaacs noted there is some precedent for more drastic steps. In the late '60s, for example, academy president Gregory Peck tried to inject more youth by stripping many older members no longer working in the industry of the right to vote.

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