Hillary Clinton has obvious attractions for liberals. She offers a solid chance of extending Democratic occupancy of the White House for four or eight years. She would realize the dream of a female president. She would appoint justices to stop the rightward drift of the Supreme Court. She would drive the tea party even crazier.
Not to mention that she's one of them. She tried to overhaul health insurance long before Obamacare. When she was a senator, the liberal blog Daily Kos gave her a lifetime rating of 94.4 (100 being the most liberal), the same as Ted Kennedy. Her 1990s credo was "It takes a village to raise a child"—a collectivist mantra if there ever was one.
But if they mass behind Clinton's presidential candidacy, liberals will be making a Faustian deal. They may get the White House. But if they expect her to implement an ambitious domestic agenda, they are in for a painful shock. It's not that she wouldn't like to achieve it. It's that her priorities will make it impossible.