“He’s got a real mess in the West Wing,” said one close presidential adviser. “Valerie is effectively the chief of staff, and he knows, but he doesn’t know. She’s almost like Nancy Reagan was with President Reagan, but more powerful.”…

Gay rights advocates say they considered Ms. Jarrett their “secret weapon” in the White House on issues like repealing the military’s policy of “don’t ask, don’t tell.” And while aides said Mr. Obama found his own way toward supporting same-sex marriage, Ms. Jarrett “reinforced his instincts,” Mr. Axelrod said. This is consistent with who you are, she told the president.

On immigration, Ms. Jarrett successfully urged the president to stop deporting certain illegal residents who arrived as children. And while some of his advisers worried about the political perils of legally challenging Arizona’s tough immigration law, Ms. Jarrett argued that its central provision — requiring the police to check the immigration status of people taken into custody — amounted to racial profiling, a civil rights issue “right in the president’s wheelhouse,” recalled Pete Rouse, another senior Obama adviser. (Ultimately, the Supreme Court upheld that provision, but struck down most of the law.)

Perhaps no policy area better shows how Ms. Jarrett can drive the White House agenda than the contraception mandate. Ms. Jarrett has a fiercely loyal following among those she backed for key positions throughout government, drawn mainly from a White House women’s network she helped build and nurture. The director of the Domestic Policy Council, for instance, previously worked for her, and she counts Ms. Sebelius, the health and human services secretary, among her good friends.