With just hours remaining before a possible government shutdown, congressional aides said Friday that it is already too late to enact a compromise 2011 budget into law.

But that doesn’t mean a shutdown is inevitable.

Instead, both Congress and the White House still have options that would keep the government running for a day — or a few days — while a broad budget agreement is written up and enacted into law.

The White House, in fact, could use obscure rules to keep the government running into Saturday. A senior government official said it could do that only if the administration had “a high level of confidence” that the House and Senate were on the verge of passing a short-term or permanent spending bill and President Obama could sign it by the end of Saturday.

The official, speaking on condition of anonymity, declined to define exactly what constituted a “high level” of confidence and said the White House is hoping not to use that option.

The other option is for Congress to simply give itself more time.

Aides said that, if both the House and Senate agree to expedite their procedures, a simple, short-term spending bill could pass both chambers before midnight.

Here’s how that might work:

Staff members would write a short bill, extending the government’s funding for a few days. It would probably come to the House Rules Committee on Friday night and, if approved by that committee, move to the House floor.

Normally, such a bill would have to wait overnight, but a vote taken Thursday erased that requirement for this measure.

Then, if the House agrees to approve the measure, it would be “prepared” by House staff. Staff members would check it for errors and be certain that it contained the text that was actually approved by the House.

Then the bill would be taken to the Senate.

That chamber has famously long and elaborate procedures, which can keep bills bottled up for days. But it also has the ability to waive them, if no senator objects.

“You can do anything by unanimous consent,” said Don Ritchie, the Senate’s historian. “But, of course, ‘unanimous’ means unanimous.”

If a single senator objected, Ritchie said, that could mean a return to the more complicated normal procedures. But it might also mean that all the blame for a government shutdown could fall directly on that senator’s shoulders — which means it doesn’t seem likely Friday night.

After that, the Senate could quickly approve the measure and send it on for the president’s signature.

All of that, of course, is predicated on the two sides reaching a broader deal. If they can’t, there may not be enough agreement to pass a stopgap measure Friday night.

So none of this might happen.

But if the Senate and House leaders decide they want to beat the clock, “it could be done,” said Jo Maney, a spokeswoman for the House Rules Committee.