A new Congressional investigation has concluded that politics played a major role in last year’s decision by federal drug regulators to bar the sale of the “morning after” birth control pill. On Monday, the Governmental Accountability Office issued a report examining why the Food and Drug Administration rejected over-the-counter sales of Plan B. For years conservative groups have opposed the sale of Plan B because some opponents of abortion consider the morning-after pill tantamount to ending a pregnancy. The GAO determined that the FDA agreed to reject over-the-counter sales of Plan B months before a government scientific review of the application was completed. The GAO also found the FDA’s decision to ignore the recommendation of an independent advisory committee as well as the agency’s own scientific review staff was unprecedented. Democratic Senators Patty Murray and Hillary Rodham Clinton said Monday that the GAO report ’’has confirmed what we have always suspected, that this was a politically motivated decision that came down from the highest levels at the F.D.A.”