Leaders from both parties in the House and Senate continue to hammer out a funding bill ahead of next week's deadline, and they say they continue to be optimistic that that the negotiations will yield a deal to avoid a government shutdown.

If for no other reason than that they know it could do lasting political damage to their party, the GOP leaders who control Congress insist they don't want to see the government close down.

Despite the chatter, what will unfold over the next week remains uncertain. Here are few questions we can answer:

What's the deadline?

If both chambers fail to pass a bill to send to President Donald Trump's desk before midnight on Friday April 28, the government would run out of money to pay its bills and a shutdown would begin.

Is that really the deadline? Can it change?

Of course, this is Congress that never finishes its work on time, so there are already discussions about needing an extension of a week or two to finish the talks and move the deal through the House and Senate. So the new deadline could shift to early May.

Who is writing the bill?

Republicans and Democrats on the House and Senate Appropriations Committees are doing much of the heavy lifting but leadership in both parties and top aides to the president will have the final say before any deal is reached.

What's the "X factor" in the talks?

In a word: Trump.

So far the President has not issued any major controversial ultimatums -- insisting on money for certain programs or barring it from others. If that changes, it could blow up the bipartisan talks.

But aides in both parties stress that this funding bill covers government operations for only the next five months. So, they might not want to wage a major battle on this bill. Republicans are also dealing with the fallout from their failure to pass an Obamacare repeal and replace bill last month. Efforts to revive that bill will be a big focus when members return next week from their two-week spring recess.

What are the potential snags?

Obamacare, of course! The 2013 government shutdown was triggered by a fight over funding the health care law. Now Trump has floated the notion of no longer continue The 2013 government shutdown was triggered by a fight over funding the health care law. Now Trump has floated the notion of no longer continue to pay the subsidies to insurance companies that keep the Obamacare marketplaces functioning. There is a legal challenge to those subsidies making its way through the courts and the GOP planned to keep paying out these subsidies while they worked to overhaul the health care system. But some outside conservative groups are trying to put pressure on Hill Republicans to halt the payments in the spending package. If they do, that could cause a major disruption in the markets. Democrats have vowed to block any bill that doesn't continue the payments.

Border wall funding: The Trump administration has already asked Congress for money to begin construction of the wall along the southwest border to make good on a central campaign promise. But Senate Democratic Leader Chuck Schumer and other top Democrats oppose the wall and say adding any money to this bill is a non-starter. Republicans have pushed for some additional funding for immigration enforcement although Schumer said that shouldn't be included either.

Defense spending: Democrats and Republicans are still battling over how much to spend on the military and how much to spend on non-defense programs. Both have caps on spending because of a previous budget agreement. Republicans insist there is an emergency need to increase military spending above the existing caps. Democrats say they also want more money for domestic priorities like medical research, environmental programs, and education - beyond what the GOP is willing to support. This continued debate could impact any final deal.

What about the House Freedom Caucus?

GOP leaders recognize that members on the far right side of the Republican caucus are likely to oppose almost any spending bill so they are not counting on support from many members of the Freedom Caucus. Instead they are working on a bill that could pass with significant Democratic support.

When is the next fight over government funding?

This bill covers the rest of fiscal year 2017, which ends on October 1, 2017. The Trump Administration is expected to submit its proposal for the fiscal year 2018 sometime toward the end of May, and the House and Senate will begin drafting spending bills for the various federal agencies. This will cover the first full year under the new administration, so the GOP may come under more intense pressure to push for its priorities, especially if efforts on health care, tax reform and other items, continue to face internal challenges.