WASHINGTON - Federal Communications Commission Chairman Julius Genachowski was expected to announce his resignation Friday after nearly four years on the job, and one public-interest group isn't sad to see him go. Public Knowledge, which has pushed for more protections for consumers against large telecommunications companies, said Genachowski's tenure "can best be described as one of missed opportunities." "The chairman had the opportunity, but declined, to take several important steps that would have promoted more robust competition in the wireline and wireless broadband markets," the group said. While Public Knowledge said Genachowski deserved credit for helping derail AT&T Inc.'s proposed $39-billion purchase of T-Mobile USA Inc. in 2011, the group said he allowed other major mergers that led to "enormous consolidation" in the marketplace for high-speed Internet service. Genachowski reportedly will announce he is stepping down just days after Republican Commissioner Robert McDowell announced he was leaving. Genachowski took over as head of the agency in June 2009 and focused on expanding high-speed Internet service. He recently has been pushing the commission to loosen its media ownership rules, which angered public-interest groups. Genachowski was expected to depart in the first half of the year because it is rare for a chair to serve more than four years. The twin departures will give President Obama the opportunity to nominate a new Democratic chairman of the five-member commission, and pair it with a Republican nominee to make it easier to gain Senate approval. Speculation about Genachowski's replacement have included Democratic FCC Commissioners Mignon Clyburn and Jessica Rosenworcel; Catherine J.K. Sandoval, a member of the California Public Utilities Commission; Karen Kornbluh, the U.S. ambassador to the international Organisation for Economic Cooperation and Development; Lawrence Strickling, head of the Commerce Department's National Telecommunications and Information Administration; and Washington, D.C., venture capitalist Tom Wheeler. Two-dozen women's rights advocates, including Gloria Steinem, co-founder of the Women's Media Center, wrote to Obama on Friday urging him to appoint a woman as FCC chair for the first time. "While there is no easy fix to getting women into the top jobs in the telecom and media industries, the government watchdog can and should be headed by a woman," the letter said. Public Knowledge said it wanted a new FCC head who would "put the public interest first." "The nation cannot afford another four years of missed opportunities," the group said.