WASHINGTON -- The State Department is poised to remove a militant Iranian dissident group from its list of foreign terrorist organizations, the culmination of a long, multi-million-dollar lobbying effort to sway U.S. politicians, officials and members of the group said Friday.

Supporters of the Mujahedeen-e-Khalq, better known as the MEK, gathered for an early celebration rally in front of the State Department hours after the news leaked that Secretary of State Hillary Clinton had sent word to Congress about the decision. Officially, the decision isn’t yet public, and lawyers for the group said they were advising caution in case there were unforeseen conditions attached to the delisting.

“The department is now in the process of sending a classified communication from the secretary to the Congress today regarding the designation of the MEK. I’m not in a position to confirm the contents of this because it’s classified,” State Department spokeswoman Victoria Nuland said.

Diplomats privately confirmed the group’s upcoming removal from the foreign terrorist organization list, with a formal announcement expected in the next week. A court order had given the State Department until Oct. 1 to determine whether the MEK still belonged on the list, based on its capacity and intent to commit acts of terror.

The group’s detractors argued that MEK operations in the 1970s killed or maimed not only Iranian targets, but also American military officers and defense contractors. The National Iranian American Council, an advocacy group for Iranian-Americans, said in a statement that it “deplores” the decision to remove the MEK because the group is widely unpopular among ordinary Iranians, including dissidents who don’t share its singular mishmash of Marxist and Islamist ideology.

“The decision opens the door to congressional funding of the MEK to conduct terrorist attacks in Iran, makes war with Iran far more likely and will seriously damage Iran’s peaceful pro-democracy movement, as well as American’s standing among ordinary Iranians,” the council’s statement said.

The group’s leadership countered that the MEK had renounced violence more than a decade ago and was committed to working with the U.S. and other Iranian opposition groups toward the peaceful ouster of the theocratic regime in Tehran. Criticism of the MEK as a dangerous, cultlike group stems from regime propaganda, members and supporters said.

“We’re jubilant, so happy,” said Shirin Nariman, a Virginia-based MEK activist who joined the rally outside the State Department. “It’s been 17 years that we’ve been fighting this. We’ve paid a heavy price, with so many dead or in prison.”

Financed by deep-pocketed donors around the world, the MEK had embarked on an ambitious lobbying effort, hiring top lawyers to represent it and paying high-profile American speakers tens of thousands of dollars each to address its cause.

The MEK convinced several retired generals, politicians and Cabinet members to support its removal from the blacklist, leading to a Treasury Department investigation this year into whether the officials were providing illegal support to designated terrorists, according to news reports. That inquiry is probably moot now.

“The MEK was placed on the FTO list in a misguided attempt by the Clinton administration to gain favor with the government in Tehran,” Rep. Dana Rohrabacher, R-Calif., said in a statement Friday. “The MEK are Iranians who desire a secular, peaceful and democratic government. Nothing threatens the mullah dictatorship more than openness and transparency.”