The government shutdown is entering its third day, with no clear end in sight. Republican and Democratic lawmakers spent much of the weekend publicly blaming the other side, while privately trying to come up with any deal that the other side can support.

It's not clear whether they will strike one anytime soon.

“We have yet to reach an agreement on a path forward that is acceptable to both sides,” Senate Minority Leader Charles E. Schumer (D-N.Y.) told reporters as the Senate headed toward a vote at noon Monday on whether to keep the government open.

Lawmakers are navigating a hornet's nest of competing issues and egos. Here are the four most significant unanswered questions that Congress must figure out to end a shutdown:

1. Will Democrats agree on a deal in which they will talk about immigration only after the government reopens? This is probably the biggest question, because it gets to two issues at the heart of this shutdown: immigration and trust.

Moderates in the Senate are trying to get both sides to agree to a deal to fund the government now and agree to debate a bill to protect "dreamers" -- immigrants brought to the country illegally as children -- later.

But Democrats fear that Republicans can't be trusted to hold up their end of the bargain. In both chambers, Republicans control what comes up for a vote. And even if a deal could pass the Senate, immigration legislation has languished in the more conservative House.

In addition, the White House has refused to offer any guarantees about what will happen after the government reopens. They've drawn a hard line: Reopen the government, then we'll talk about talking about legislation.

2. What does President Trump do? There's a strong case to make that Trump's indecisiveness was a major factor in this shutdown.

Democrats said that in the days leading up to the shutdown, they offered taxpayer money twice for Trump's border wall in exchange for protections for dreamers, and twice, he seemed receptive, then suddenly rejected it. (Once with profanity heard round the world.)

As my colleagues on Capitol Hill report, Democrats' trust in the president to negotiate is lower than low:

Schumer on Sunday said that in the hours before a shutdown, Trump “picked a number for the wall, and I accepted it.”
“It would be hard to imagine a much more reasonable compromise,” he added. “All along, the president saying, ‘Well, I’ll do DACA, dreamers, in return for the wall.’ He’s got it. He can’t take yes for an answer. That’s why we’re here.”

3. Will rank-and-file Democrats even accept a deal that includes funding for Trump's border wall? In the House, top Democrats seem split. Rep. Luis V. Gutiérrez (D-Ill.) told ABC News that he would reluctantly do that, saying: “I think the wall is a monumental waste of taxpayer money. Having said that . . . if that’s what the hostage takers [demand for] the dreamers, if that’s their ransom call, I say pay it.”

But when reporters asked House Minority Leader Nancy Pelosi (D-Calif.) if she would accept a deal that put $20 billion toward Trump's wall, her answer was simply: “Oh, come on.”

It's easy to see why Pelosi considers that idea absurd. Trump's wall has become a symbol of everything the left despises about the president. Even Republicans from border states have been reluctant to support a wall.

The public is skeptical, too. Majorities of Americans oppose a border wall (63 percent), according to a new Washington Post-ABC News poll. That includes 68 percent of independents and 86 percent of Democrats.

Those numbers pose a risk for Democrats who put the border wall on the negotiating table to end this shutdown: Are they successfully negotiating one popular thing (getting a deal to protect dreamers) at the expense of something extremely unpopular (funding Trump's border wall)?

4. Even if the government reopens, now what? Even when the government reopens, it probably will be with just a short-term spending bill that doesn't change funding levels from last year. Congress has been relying on a lot of those lately. This would be the fourth one of these short-term spending bills Congress has had to pass since the fiscal year started in October.

The stop-and-start nature has some normally reliable Republicans frustrated, so frustrated that they voted against last week's short-term spending bill on principle.

“I’m tired of it. This is the fourth one we’ve done, and you’re killing the military,” Sen. Lindsey O. Graham (R-S.C.) told reporters last week.

Put another way: Congress can't agree right now to fund the government for a couple of weeks, let alone for the rest of the fiscal year.

Reopening the government probably won't solve any of the institutional problems that got Congress in this mess in the first place: debates about where to raise spending, funding for disaster aid, the opioid crisis, partisanship and competing factions within parties. Which means: As soon as we get out of this shutdown, Congress is potentially at risk of another.