WASHINGTON - US President Barack Obama said that he remains confident that a government shutdown can be avoided this weekend if negotiators can build on constructive talks held at the White House.

Obama spoke after a hastily arranged late-evening White House meeting with Republican House of Representatives Speaker John Boehner and Democratic Senate Majority Leader Harry Reid. The three met for roughly an hour and 15 minutes.

The session underscored the stakes of the deepening political fight as time grew short.

After huge wins in last year's House elections gave them control of the lower chamber, Republicans have vowed to slash spending and bring the US deficit under control.

Lawmakers must reach a deal by Friday at midnight, when a temporary government funding bill is set to expire. Federal agencies' day-to-day operations through the end of the budget year are at stake.

Differences remain despite the progress, but Obama announced on Wednesday night that talks would continue through the night in hopes of avoiding a government shutdown.

"It's going to require a sufficient sense of urgency," Obama said, "to complete a deal and get it passed and avert a shutdown".

Obama emerged before reporters to declare his differences with Republicans in the House were narrowing but that both sides were still stuck in an impasse.

"I thought the meetings were frank, they were constructive," Obama said, "I remain confident that if we're serious about getting something done, we should be able to complete a deal and get it passed and avert a shutdown. But it's going to require a sufficient sense of urgency from all parties involved."

Boehner criticized Obama, though he said he likes the commander in chief personally.

"The president isn't leading," Boehner said. "He didn't lead on last year's budget, and he's not leading on this year's budget."

Obama has already ruled out the weeklong measure Republicans intend to push through the House, and Senate Democrats have labeled it a non-starter. Republican officials said the details of the bill could yet change. But passage of any interim measure is designed to place the onus on the Democratic-controlled Senate to act if a shutdown is to be avoided.

The White House used its unmatched megaphone to emphasize the stakes involved in the negotiations, arranging a briefing for the presidential press corps on the ramifications of a partial government shutdown.

National parks would close, as would the Smithsonian Institution and its world-class collection of museums clustered along the National Mall within sight of the Capitol.

NASA spokesman Bob Jacobs said he was unable to predict what the impact would be on preparations for the shuttle Endeavour's flight on April 29, or Atlantis' trip into space on June 28.

Senator Dick Durbin, the No 2 Senate Democrat, hinted at movement in the talks. "There's been a direct negotiation - things put on the table that had not been discussed before - and I think we're moving" toward agreement, he said.

AP