The gay rights organization Human Rights Campaign has appointed Chad Griffin, a former Clinton White House official, as its next president.

Beginning in June, he will replace Joe Solmonese, who announced last year that he was leaving the HRC to pursue new career opportunities.

In a letter announcing Griffin’s selection, Solmonese called his successor “the mastermind behind the federal lawsuit to overturn California’s Proposition 8,” which prohibited gay marriages.

“Chad’s spent his career taking on the toughest fights against entrenched, well-financed interests,” Solmonese wrote. “He’s passionate about our equality and more importantly, has a proven track record of consistently delivering results. Already, the fight to overturn Prop. 8 has prevailed in two federal court rooms.”