AP

The Capitol is seen in Washington after dark. Work is intensifying in Congress to reach a deal on long-overdue legislation to finance the government through the end of September and avoid a government shutdown.

From NBC's Shawna Thomas, Kelly O'Donnell, and Carrie Dann
As talks continue on an eleventh-hour budget deal that could forestall a government shutdown, House Republican members have been given guidance to stick around this weekend rather than leave Washington for their home districts, a House aide tells NBC News.

The instructions mean that House leaders could be planning for a weekend session of Congress to pass some form of compromise legislation to keep a potential government shutdown from spilling into the work week next Monday.

But, while House and Senate aides say that talks are still ongoing, a concrete plan to avoid a shutdown is far from in place. The administration and congressional leaders scuttled a potential White House meeting this morning until after further negotiations.

The president, who is traveling to Philadelphia and New York today, may call congressional leaders back to the White House late tonight, Senate Majority Leader Harry Reid told NBC News.

House Speaker John Boehner and Obama spoke by phone this morning. During the call, which lasted about three minutes, the speaker told the president that he "remains hopeful a deal can be reached," according to Boehner's office.

Reid also spoke to Obama shortly before noon today.

Reid told NBC that there could be room for compromise on the issue of policy “riders” – Republican add-ons to the budget bill that have proved sticky for negotiators trying to reach a deal.

Democrats could be amenable to riders related to the maintenance of the detention center at Guantanamo Bay and a scholarship program for D.C. schools favored by House Speaker John Boehner, Democratic aides say.

But, Reid reiterated, GOP riders that would defund Planned Parenthood or pull funding for the implementation of the health care law are still flatly unacceptable to Democrats.

Even as the details of a deal continue to be hashed out, it’s unclear what form a bill to keep funding the government would take.

There appears to be no movement on one previously-floated idea on the House side -- a two or three day continuing resolution that would keep the government running for a handful of extra days as talks continue. Republicans have also not determined whether or not to bring a proposal to the House floor that would cut $12 billion from current levels – an offer that was rejected by the White House earlier this week.

The current government funding measure runs out on Friday, April 8.

*** UPDATE *** NBC's Luke Russert reports that House GOP leaders, accusing the president of "not leading" on the budget, now say that they will call for a vote tomorrow on the one-week budget extension that cuts $12 billion and extends DoD funding for the rest of the fiscal year.