For the first time since 2013, the United States government could be on the verge of a partial shutdown. If Congress cannot approve a spending bill by Friday night, government operations deemed “inessential” will be forced to shut down until a spending agreement can be reached.

As Republicans attempt to unite their 51-member Senate majority behind a single short-term spending bill to avert a shutdown, Democrats are demanding cooperation on a number of key issues. Congress has delayed the showdown by passing a series of continuing resolutions that repeatedly pushed the final deadline back, but some lawmakers have indicated that they believe the time has come to reach a final budget for fiscal 2018.

An additional short-term continuing resolution proposed by House Republicans would provide stopgap funding through Feb. 16, but not all Republicans are on board. Rep. Austin Scott, R-Ga., warned that CRs — and the financial uncertainty they bring — hurt the military. The House Freedom Caucus has also expressed frustration with the bill.

Whether it’s accomplished in a few more days or a few more weeks, however, it is clear that Congress must ultimately reach an agreement on major spending issues or risk closing down federal agencies and furloughing hundreds of thousands of employees.

With the midterm elections less than a year away, neither party is eager for the negative attention a shutdown would bring. President Donald Trump has repeatedly blamed the Democrats for the possibility of a shutdown, although a recent Hart Research Associates poll indicated that a plurality of Americans would blame Trump and the GOP for a shutdown, instead of the Democrats.

On Thursday, Trump further complicated negotiations by objecting to GOP leadership plans to link a new continuing resolution to a six-month extension of the Children’s Health Insurance program. Trump said that an extension of children’s health program “should be part of a long term solution” and not a  stopgap spending plan.

With so much to lose, why would Congress risk a shutdown? Eight  major policy issues have come to dominate the spending debate, and it’s not clear than any have easy solutions.

Deferred Action for Childhood Arrivals (DACA)

One of the most hotly contested issues this winter has been the possible renewal of DACA, a popular Obama administration policy that attempted to establish protections for people who had been brought illegally to the United States as children.

Under DACA, those residents could apply for two-year permits to work and study in the United States; they also received temporary protection from deportation. The Trump administration announced last September that it would end the program, which currently protects around 700,000 residents, in March, unless Congress intervenes to continue the program. DACA also enjoys enormous public support — a recent CBS News poll indicated that 70 percent of Americans supported allowing DACA recipients to stay in the United States.

Democrats have indicated their refusal to support any spending bill that does not include protections for DACA recipients.

Comprehensive Immigration Reform

The DACA issue is one key component of a larger debate over immigration. Trump famously ran on his promise to construct a wall on the Mexican border, banning immigrants from places like Syria and implementing “extreme vetting” to keep potential security risks out of the country.

But these hardline stances are not universally supported among Republicans. It seems likely that any successful immigration deal will have to include at least some bipartisan support, and Democrats seem unwilling to budge on certain key issues like DACA protections.

A bipartisan deal proposed by the so-called “Gang of Six” senators looked to be a possible out for both sides. At a meeting to discuss the proposal, however, the president allegedly asked why the United States would take immigrants from “s—hole countries,” a comment that drew widespread condemnation and effectively derailed the immigration debate.

Rep. Mark Meadows, R-N.C., and Rep. Bob Goodlatte, R-Va., are reportedly working on an alternate immigration bill. But that bill is expected to be too conservative to achieve majority support, especially given Republicans’ single-vote majority in the Senate.

Border Wall

Another major component of the immigration reform debate, the border wall was one of Trump’s flagship campaign promises. His promise that Mexico would pay for that wall, however, seems unlikely to come to fruition, meaning that border wall spending might make an appearance in an ultimate draft of the spending bill.

The administration recently requested $18 billion over the coming decade for the wall, but then Trump upped the ante to $20 billion to cover the total cost of the highly controversial project.

However, the wall’s unpopularity among Democrats and moderates means that this issue could be a sticking point if Republicans attempt to move forward with funding it. Moreover, its unpopularity with many voters makes it a risky issue to motivate a shutdown, especially in an election year. A recent Politico/Morning Consult poll found that more than half of Americans said a border wall was not worth a government shutdown.

Defense and Domestic Spending

Various members of the House and Senate Armed Services Committees have warned that frequent continued resolutions are crippling the military, which relies on stable funding. This might make hawkish lawmakers more willing to compromise, but many Republicans seem eager to achieve big increases in defense spending.

However, other Republicans, particularly libertarian-leaning ones like Sen. Rand Paul, R-Ky., are wary of significant spending increases. As a result, a successful bill may require bipartisan support to pass.

The issue here is that Democrats, amid fears that December’s tax cuts will necessitate cuts to domestic programs, want an equal increase in domestic spending to match any increase in defense. The original GOP budget proposal would have increased defense spending by $54 billion and domestic by $37 billion. Democrats want both types to increase by the full $54 billion.

Disaster Relief

2017 was a particularly deadly year for both hurricanes and wildfire, demonstrating the paramount importance of funding for disaster relief. The House passed an $81 billion disaster aid package in December with bipartisan support, but the bill has not yet made its way to the Senate due to opposition from Democrats.

Although Puerto Rico is not represented by a voting member in Congress, its people are among the Americans who are most in need of disaster relief, as recovery from Hurricane Maria continues to be sluggish.

Children’s Health Insurance Program (CHIP)

One of the features of the Republican stopgap bill — the one that would continue funding through February — is a six-year extension for the Children’s Health Insurance Program. CHIP provides health insurance to nearly 9 million children and is jointly funded by state and federal government.

Federal funding for CHIP expired in September as Congress let the program lapse, despite wide bipartisan support. If Congress doesn’t approve new funding by the time the resolution expires, the program will start shutting down. CHIP will still be a major issue for the spending bill, therefore, regardless of whether Republicans’ latest stopgap bill goes through.

Obamacare Subsidies

The Affordable Care Act provided for government subsidies that reduced the cost of health insurance for lower-income Americans. These subsidies were designed to make health insurance more affordable for a wider range of consumers, thereby increasing the number of people buying health insurance. However, in October the Trump administration announced that they would be ending these subsidies.

A bipartisan bill by Sens. Patty Murray, D-Wash., and Lamar Alexander, R-Tenn., would continue funding the ACA subsidies, and Democrats may push for this spending to be a part of the overall bill. However, allocating funding for Obamacare subsidies may alienate conservatives like the members of the House Freedom Caucus, who have warned that they may refuse to support a budget that provides those subsidies.

Planned Parenthood

Federal funding for Planned Parenthood was a major issue during budget debates in the spring of 2017, and the controversy will likely persist as lawmakers debate this year’s bill. Democrats have demanded that any acceptable spending bill must fund Planned Parenthood and other women’s healthcare providers.

Under the Hyde Amendment, federal funding cannot be used to pay for abortions. Federal funding for Planned Parenthood instead largely takes the form of Medicaid reimbursements for women who seek other procedures from the organization’s clinics, including cancer screening and gynecological care.