WASHINGTON (Reuters) - The NAACP is dismissing its president as the biggest U.S. civil rights organization tries to recast itself to strengthen its advocacy role and better support local activism, officials said on Friday.

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Cornell Brooks, who also had been chief executive of the National Association for the Advancement of Colored People since mid-2014, will not have his three-year contract renewed when it expires at the end of June, NAACP Chairman Leon Russell said.

Brooks’ dismissal comes as the 108-year-old NAACP is preparing to rebuild itself to face such issues as voter rights, environmental protection, education, police brutality and education, Russell said.

“That’s why we are launching today a systemwide and strategic revisioning process that will ensure that the NAACP can address these 21st century challenges,” he said in a conference call with reporters.

Russell and Vice Chairman Derrick Johnson will run the Baltimore-based NAACP on an interim basis during the search for Brooks’ replacement.

Russell said the process might take a year, during which the group’s board would gather comment from members nationwide about the NAACP’s future course.

The NAACP has been a leader of U.S. civil rights since its founding in 1909. Its pre-eminence has been challenged by the Black Lives Matter movement that sprang up to protest police shootings of African Americans in recent years and by mass protests against President Donald Trump.

Johnson said the group wanted to strengthen local and state activism and education and develop local leadership.

The decision not to renew Brooks’ contract was made by the NAACP national board on Friday.

“I’m disappointed and mystified,” Brooks said in a telephone interview. He said that, including interim leaders, he was at least the 10th head of the NAACP in 15 years.

“There’s been a revolving door of CEOs at the NAACP and this is a bad moment for it to be spinning,” he said.

Brooks, a lawyer and minister, said membership and donations had increased during his tenure and NAACP lawyers had won nine court cases in 10 months over voter suppression.