Washington (CNN) It's the end of a year that has left Republicans with little to show for their sweeping control of the government -- and now, it's crunch time.

With little more than four weeks -- and just 12 scheduled legislative days left -- and the 2018 midterm elections looming, Republicans must not only pass their contentious tax overhaul and avert a government shutdown , but also reauthorize other federal programs that are fraught with politics.

The final sprint to 2018 will test the party's leadership and force the GOP to come to terms with whether they are a governing party or one too mired in intraparty squabbles to function.

"To every Republican senator: The fate of the party is in our hands, as well as that of the economy," Republican Sen. Lindsey Graham told CNN's Dana Bash Sunday on "State of the Union." "The economy needs a tax cut, and the Republican Party needs to deliver, so I think we'll get there."

The next month will also test the Democrats' stamina and ability to force their own agenda in Trump's Washington.

For a body that has been engulfed by partisan rancor and has few legislative successes, Congress has more work to do in December than it has been able to finish in months. The need to actually govern or face a shutdown, as well as deal with an end to a key spying program and the evaporation of a bipartisan children's health insurance program, comes as allegations of sexual harassment befall the Capitol, creating a tense and uneasy atmosphere that is permeating Washington.

It would be a massive undertaking in any year, but for Republicans -- who now control the House, Senate and White House -- it is the ultimate test.

Spending bill

This is the biggie. The government runs out of money on December 8 and already members are talking about a potential short-term extension to keep the government running while lawmakers negotiate a bigger spending deal before lawmakers depart for the holiday.

That still doesn't leave lawmakers with much time to settle on a plan and avoid a Christmas shutdown in Washington. Republicans and Democrats are still working through the government spending caps for military and non-military funding, and some Democrats are also pushing to including protections in the bill for individuals who entered the US illegally as children, who previously benefited from the Obama-era Deferred Action for Childhood Arrivals program.

Expect it to make for a very messy few weeks in Washington as leaders on both the Republican and Democratic sides of the aisle struggle to find a way to cut a deal that also satisfies their rank-and-file members.

Sexual harassment

In recent weeks, the Hill has been awash in reports of alleged sexual harassment against sitting members of Congress. First, Democratic Sen. Al Franken was accused of groping and forcibly kissing broadcaster Leeann Tweeden. Others have since alleged he groped them. Then, BuzzFeed News published an explosive report that the longest-serving man in Congress, Democratic Rep. John Conyers, settled a wrongful dismissal complaint in 2015 after allegedly sexually harassing a staffer. Conyers has "expressly and vehemently" denied the allegations.

Top Republicans -- with the exception of President Donald Trump -- have distanced themselves from GOP Alabama Senate candidate Roy Moore after several women accused Moore of pursing sexual relationships with them when they were in their teens and he was in his 30s.

One woman alleges Moore touched her inappropriately when she was 14. Another woman has accused Moore of sexually assaulting her when she was 16. The legal age of consent in Alabama is 16.

Moore has repeatedly denied the allegations.

While Republicans are trying to stay focused on their domestic policy agenda, there is little disputing that Congress has a serious issue on its hands that it may have no choice but to deal with sooner than later.

Already, a group of lawmakers has proposed legislation to revamp the system individuals face when alleging sexual harassment, and the House will vote this week on a bipartisan resolution mandating sexual harassment and anti-discrimination training, which is expected to pass overwhelmingly.

Tax reform

This is the defining piece of legislation for Republicans this year -- and given their failure to repeal Obamacare -- the thing they cannot afford to mess up. So far, signs are promising that Republicans might be able to deliver.

House Republicans managed to pass their bill 227 to 205 before taking off for Thanksgiving. Now, the onus falls on the Senate, where Majority Leader Mitch McConnell can afford to lose only two votes.

While things look to be moving in the right direction, there are still more than three Republican lawmakers who have stopped short of fully endorsing the Senate tax bill.

But passing the bill out of the Senate is just the next step in a multi-pronged process. Republicans will still have to find a way to bridge massive differences between the House and the Senate proposals. It's a process that will include tedious negotiations over a popular state and local tax deduction that the Senate bill fully repeals, but the House legislation partially maintains. The Senate bill also repeals the individual health insurance mandate, while the House bill does not.

Republican lawmakers, however, say failure is not an option. After the Senate Republicans voted against overhauling the Affordable Care Act this summer, President Donald Trump is desperate for a win. The President is expected to meet rally Senate Republicans Tuesday on Capitol Hill during their weekly lunch.

Immigration

Officially, the deadline for Congress to act on the Deferred Action for Childhood Arrivals (DACA), which protects individuals who came to the US illegally as children from deportation, doesn't come until March. But some Democrats are emphatic that the issue must be included in the contentious fight over government funding.

A group of liberal Democrats have signaled they'd be willing to shut the government down over any impasse on DACA, a problem that Republicans -- who control both the House and Senate as well as the White House -- could still be blamed for.

House Minority Leader Nancy Pelosi told reporters last week that she would wait to see what exactly was in the spending bill, but she will press for action.

"We will not leave here without the DREAM Act passing with a DACA fix," she said referring to a pair of immigration measures.

Republican leaders, meanwhile, are facing pressure from their right flank not to blink and negotiate with Democrats on DACA in December. Instead, those conservatives advocate waiting until the deadline grows closer, when they believe they will have more leverage to negotiate enhanced boarder security provisions in exchange for the DACA recipient protections.

Obamacare spending

The future of the Affordable Care Act remains as uncertain as ever. After Trump announced earlier this year that he would cease making what are known as cost-sharing reduction payments, which help offset the cost on insuring low-income people, Democrats and Republicans found a compromise that could help protect consumers from what experts predict could be spiking premiums in upcoming years.

But, so far, there is no sign that the bipartisan bill -- authored by Sens. Lamar Alexander, R-Tennessee and Patty Murray, D-Washington, will get a vote by the end of the year.

The bill has stalled in the House and Senate as Trump and many rank-and-file Republicans have dismissed it as little more than an insurance bailout that would protect the Obamacare marketplace. The future of the legislation is even more uncertain now that the Senate's tax bill includes a repeal of the individual mandate, which would repeal the penalty individuals pay if they don't have health insurance.

Children's health insurance program

Federal funding for the children's health insurance program ended in September, but many states have been able to keep their programs afloat in the intervening weeks. That changes at the end of December and early January, when five states and the District of Columbia are projected to run out of the federal money that keeps their programs operating, according to a report from Georgetown University's Center for Children and Families

The bipartisan children's health care program is estimated to provide health insurance for about 9 million children across the country, but political infighting over how to cover the cost of the program has stalled Congress' progress. The House passed a bill to reauthorize funding for five years, but Democrats accused the GOP of using the bill to carve out key protections in the Affordable Care Act.

Lawmakers are still trying to agree on how to fund the program, but time is running out. While the federal government has some emergency funds it can dole out, other states will have to find a way to shore up the extra money themselves. Some states are preparing to send letters to constituents to notify them that the money may be running out in upcoming weeks.

Spy program

A key spy program will sunset at the end of the year pitting privacy advocates and national security hawks against each other once again. The showdown is over section 702 of the Foreign Intelligence Surveillance Act, which gives the US broad authority to intercept electronic communications from foreigners abroad, but has also incidentally intercepted communications between those individuals and Americans.

The intelligence community maintains that the program is essential to US national security and does not and is not allowed to target Americans in any way. But privacy advocates have argued it provides a backdoor to the US government to intercept the communications of its own citizens.

There are several competing proposals in the House and the Senate out there. Some reauthorize the program for several more years, but include additional protections or transparency provisions. Another proposal by Republican Sen. Tom Cotton of Arkansas -- backed by Trump administration officials -- would permanently extend the program as is.

It's hard to predict how this fight will end as the program scrambles traditional party lines and has attracted peculiar political pairings in the past. It's possible Congress could vote for a short-term extension of the program to allow themselves more time to negotiate next steps.

Flood insurance

Along with funding for the government, the National Flood Insurance Program expires December 8. The battle over how to both reauthorize and reform the program has been brewing all year, but it comes to a head again early next month.

Here's the hold up: House Republicans passed legislation in November that would overhaul the program, but many senators on both sides of the aisle have objections to it. The House-passed bill would give private flood insurance companies more leeway to compete against the government's sponsored program and would limit the protections for individuals who live in flood-prone zones where policies are paid out repeatedly.

The fight over flood insurance comes after a series of devastating hurricanes left families in Texas, Florida and Louisiana reeling this year.