US lawmakers have urged the Bush administration to be transparent on its controversial nuclear co-operation proposal with India.
India is looking at nuclear power to meet its energy needs
Members of Congress' International Relations Committee chided the State Department for giving few details about the 18 June agreement.
Their comments came at hearings on the deal that covers greater co-operation in civilian nuclear energy.
President Bush hopes it will be in place when he visits India in 2006.
Critics say the proposal could undermine efforts to curb the spread of nuclear weapons technology.
They also say it reveals double standards, with the US apparently prepared to overlook India's secret development of a nuclear weapons capability while putting pressure on Iran and North Korea over their suspected nuclear weapons ambitions.
Supporters say India has been a model of responsibility on the proliferation front.
"As it stands, the situation is both strange and unusual in that the Indian authorities know more about this important proposal than we in Congress," said Henry Hyde, Republican chairman of the International Relations Committee.
Mr Hyde said Congress had received "little if any information" from the Bush administration regarding key details of the proposal.
He added that both the House of Representatives and the Senate had written to Secretary of State Condoleezza Rice, requesting the administration to begin urgent consultations on the deal with Congress.
The complex deal is still being negotiated between Washington and Delhi.
The US Congress will have to change national law for the proposal to go through.
The BBC's world affairs correspondent, Nick Childs, says some in Congress are clearly unhappy at the deal.
He says it could be a bumpy political and diplomatic ride between now and Mr Bush's trip to India early next year.