Here are the issues Congress will most likely deal with, ranked.
1. Fund the government by Jan. 19: Congress could not agree on how to fund the government in 2018, so they kicked the can down the road. Now they have a little more than two weeks to either stall again or come to a bipartisan agreement.
The hang-ups: Republicans need Democrats and/or conservative House lawmakers to pass a spending bill, which means any one of these factions of Congress could decide to leverage their votes for a policy issue that is a non-starter for the other side.
Republicans are loath to step on their tax bill success by shutting down the government.
Molly Reynolds, a congressional expert with the Brookings Institution, thinks Congress might have to buy more time by passing another short-term budget.
2. Get a deal ending automatic spending cuts: Complicating already-complicated budget negotiations are strict caps on how much Congress can spend each year on domestic and defense spending, a requirement from a 2011 budget deal.
Both Senate Republicans and Democrats say ending these automatic spending cuts is their priority. They must find a way to raise these caps if they want to come to a long-term spending deal.
The hang-ups: Republicans are focused on raising the caps for military spending to give President Trump his requested increase of about $100 billion. Democrats are demanding a dollar-for-dollar raise on domestic spending, too. (Things like housing programs, Pell grants, and food and job assistance.) That could turn off some fiscally inclined Republicans, putting the whole spending bill in jeopardy.
3. Fund the Children's Health Insurance Program and disaster relief: Lawmakers on both sides generally agree they need to refund CHIP, a program 9 million children rely on that Congress let expire in September. (Right before the holidays, they infused $3 billion to keep it afloat for the next few months.)
Another must-do is issuing tens of billions of dollars to communities ravaged by historically strong hurricanes and wildfires. Republicans and Democrats generally agree helping communities rebuild is a core function of the federal government.
The hang-ups: The money. (Always the money.) On disaster relief, it may just be too expensive for a majority of Congress to stomach. Before the holiday, the House approved $81 billion in disaster relief, but Democrats said that was not enough, given places like the U.S. Virgin Islands and Puerto Rico still do not have power. One Texas congresswoman, Rep. Sheila Jackson Lee (D), has said she thinks recovery from Hurricane Harvey alone will cost $150 billion.
4. Protect dreamers: Four months after Trump ended the program that protects young undocumented immigrants, and then tossed it to Congress to deal with, lawmakers haven't figured out what to do.
There is a bipartisan group in the Senate trying to put a deal together. Powerful GOP senators such as John Cornyn (Texas), Charles E. Grassley (Iowa), John McCain (Ariz.) and Jeff Flake (Ariz.) support dreamer protections.
The hang-ups: It seems that for every Republican who wants dreamers protected, there is another Republican, such as Rep. Steve King (R-Iowa), who sees it as amnesty.
5. Propping up subsidies for Obamacare: This is top priority for one Republican in particular, Sen. Susan Collins (Maine). She got an agreement from Senate Republican leaders that she would vote for the tax bill IF they voted on a bipartisan bill to continue payments that help lower-income people with health-care costs.
The hang-ups: A vote in the Senate doesn't mean a bill will become a law. House Republicans don't seem too interested in voting on something that could save Obamacare, especially when a number of them are still peeved that Obamacare even exists.
“She may be out of luck,” said Steve Bell, a former GOP budget analyst, now with the Bipartisan Policy Institute.
6. Renewing FISA: Should the government be able to spy on a foreigner without a warrant? And, in the process, collect any communication that foreigner has with Americans? A program that lets the government do that, known as FISA, expires on Jan. 19. A House aide predicted to The Washington Post's Jeff Stein the issue will get a vote in the next few weeks, which means Congress could have a potentially contentious debate on its hands.
The hang-ups: The debate over warrantless surveillance isn't new, and it doesn't fall along party lines. Those who think the program opens the door for abuse of government power include libertarian-minded Republicans such as Sen. Rand Paul (Ky.), as well as liberal Democrats.
Reynolds said Congress has enough trouble navigating Republican vs. Democratic dramas, so doing this could get tricky.