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The kidnapping of nearly 300 Nigerian schoolgirls by radical Islamic terror group Boko Haram has drawn international condemnation, including that of former Secretary of State Hillary Clinton.

"Abominable," is how she described the kidnapping, calling it an "act of terrorism" that merits "the fullest response possible."

But the State Department, under Clinton's leadership, repeatedly resisted and blocked efforts to designate Boko Haram as a terrorist group. Those who pushed for the designation as early as 2011 are now saying the department missed a major opportunity to track and target the deadly organization as it grew.

"The delayed designation of Boko Haram as a Foreign Terrorist Organization cost us two years of increased scrutiny of the group's activities and leadership," Rep. Patrick Meehan, R-Pa., said Thursday in a statement to FoxNews.com. "Boko Haram met the statutory requirements for the designation as early as 2011, but the State Department's delay has left us with fewer resources and less intelligence on an Islamic terrorist group with ties to al-Qaeda that is clearly destabilizing the region."

The State Department did label Boko Haram as a foreign terrorist organization in November 2013, under the leadership of Secretary John Kerry.

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    But Boko Haram had been killing people for years at that point, building ties with Al Qaeda sympathizers and orchestrating major terror attacks, including one on a U.N. compound in 2011.

    Shortly after that attack, lawmakers began lobbying the State Department to consider labeling Boko Haram a terrorist organization, to no success.

    A March 30, 2012, letter from Rep. Peter King, R-N.Y., and Meehan urged Clinton to "immediately designate" the group, citing estimates that it had killed more than 900 people in the last two years.

    The lawmakers noted that designating Boko Haram would authorize a range of punitive measures -- giving the Justice Department clearance to prosecute those tied to the organization and the Treasury Department the ability to go after members. The letter said those in the intelligence and law enforcement community were "deeply" concerned about the group's "rapid progression from a machete wielding mob to a full blown al Qaeda affiliate."

    Indeed, just a few months later Reuters first reported that a high-level Justice Department official had sent a letter to the State Department urging them to place Boko Haram on the terror organization list.

    The department still resisted. Further, the department reportedly lobbied Congress to stall legislation seeking the designation.

    At the time, a department official told Reuters they were "very concerned" about violence in Nigeria but stressed that adding a group to the list is a "rigorous process which has to stand up in a court of law."

    According to The Daily Beast, State Department officials now argue there was concern at the time that putting Boko Haram on the list would raise its profile and give it "greater credibility," in turn helping recruitment.

    But one unnamed former U.S. official told The Daily Beast that everyone from the FBI to the CIA was urging the department to make the call, calling Clinton's recent comments "gross hypocrisy."

    Asked Wednesday why it took so long to place Boko Haram on the list, department spokeswoman Jen Psaki said she could not comment on "internal decision making" but noted that the eventual decision in November to designate them "sends a strong message about how concerned we are about them."

    A State Department official noted Thursday that the department did designate three Boko Haram-tied individuals in June 2012, including the group's leader. This was followed, the official said, by an "extensive process of review and research" on possible designation of the group itself.

    "After that review and consultations with the Nigerian Government and other partners, we determined that designating these groups was both appropriate and effective in helping advance our larger counterterrorism strategy," the official said, referring to the November 2013 decision.

    Timothy Furnish, an author and Islam scholar, told Fox News that the department probably was reluctant "to add another group that is clearly Islamic to the list."

    "Better late than never, but unfortunately where were these tweets and where was this outrage when churches were being bombed and thousands of Christians -- and other non-fundamentalist Muslims -- were being killed in Nigeria?" he said, referring to a recent Clinton tweet drawing attention to the kidnappings. "It would have been nice if this outrage had happened earlier."

    FoxNews.com's Judson Berger and Fox News' Jonathan Hunt and Lucas Tomlinson contributed to this report.