"We are discussing with the administration what is needed, and I think that all of us are very concerned about what's happening in Pakistan," Democratic House Majority Leader Steny Hoyer told reporters.

Republican Senator Jon Kyl described the monies as a down payment of sorts on 1.4 billion dollars in Pakistan aid included in an 83.4-billion-dollar emergency spending bill that may not clear the US Congress before July.

"I just returned from Pakistan, and the situation there is deteriorating," Kyl told reporters, warning that "if we were to wait until roughly close to the 1st of July, it could be too little, too late."

"The administration is looking right now at pulling a small part of that money out, somewhere between 200 million dollars and 400 million dollars, for both counterinsurgency and economic assistance, that we could pass really quickly, in just a matter of days," said Kyl.

Even as US military and diplomatic officials praised Pakistan for military operations against Taliban militants in the northwest and voiced hope the offensive would be sustained, lawmakers expressed deep concerns.

"Bottom line with Pakistan: It is terribly worrisome. It's probably the place that most people worry about the most right now," said Democratic Senator Chuck Schumer, who predicted Democrats would be "strongly supportive" of urgent US aid for the "war on terrorism" ally.

Hoyer, Democratic House Speaker Nancy Pelosi, and other key lawmakers were to meet later Tuesday to discuss the matter and try to map a way forward, said a Democratic aid, who requested anonymity.

Obama's special envoy for Pakistan and Afghanistan, veteran diplomat Richard Holbrooke, made the case for urgent aid in meetings with top Democrats in recent days, another a Democratic congressional aide told AFP.

That aide said it was not clear how much support existed in the US Congress for speeding financial assistance to Pakistan amid concerns that US aid does not reach the Pakistani people.

But Hoyer said lawmakers would act: "If something needs to be done, I think the answer to your question is we're going to address it."

"Pakistan in many ways is of higher concern right now than Afghanistan," he said. "And Afghanistan is something that has a high level of concern as well.

"I think everybody's concerned about what's happening there, what's happening with the Taliban. The stability of Pakistan is very, very important to not only the region but to the United States as well."

The Wall Street Journal, citing unnamed sources, reported that, barring congressional action, Obama could seek to push the money through presidential actions that may not require congressional support.