By Corey Mitchell

Democratic U.S. Sen. Amy Klobuchar is joining a group of lawmakers calling for tougher international sanctions against an organization that kidnapped more than 200 girls in Nigeria last month.

Klobuchar signed on to a letter Tuesday to President Obama, urging him to advocate for tougher international sanctions against Islamic terror group Boko Haram, which has claimed responsibility for the kidnappings. All 20 women sentaors signed the bipartisan letter.

Islamist militant group, Boko Haram, kidnapped 276 schoolgirls in Nigeria last month. Leaders of the terrorist group have said they will sell the girls.

“This heinous crime demands that we take action immediately," Klobuchar said on the Senate floor this week.

The letter urges the White House to press for Boko Haram to be added to the United Nations Security Council's al Qaeda sanctions list, which would prompt other nations to impose sanctions. The U.S. is already sending a team of military and law enforcement officials to advise the Nigerian government.

Klobuchar also signed a letter to Obama with Republican Sen. Mark Kirk of Illinois, urging "a significant worldwide response to help rescue the abducted girls, combat Boko Haram in Africa, and stand against the broader threat of modern-day slavery."

In response to the international outcry over the brazen abductions, Obama said the United States will do everything it can.