The Republican legislative agenda for the remainder of the year was thrown into question Tuesday after the Trump administration announced its decision to gradually wind down an Obama-era program affecting undocumented immigrants brought to the United States as children.

The White House essentially put Congress on a six-month clock to advance a comprehensive immigration overhaul, an achievement that has so far been unreachable for many years due to the complexity of the issue and vast differences of opinions.

But with few remaining legislative days in September and a long to-do list, the question of what to do with the Deferred Action for Childhood Arrivals program — or DACA as it is commonly known — could derail GOP plans to revamp the U.S. tax code, as well as other big ticket legislative items.

Republicans are still debating how to address several upcoming deadlines, including the pending debt limit and how to fund the government beyond the end of September. The House and the Senate are also expected to act this week on legislation to provide relief funding to areas hit by Hurricane Harvey.

A so-called clean increase to the debt ceiling could be attached to the hurricane relief bill in the Senate, aides said, and sent back to the House for consideration. Another option would be to add both measures to whatever mechanism Congress uses to fund the government past September, likely to be a short-term continuing resolution that would tee up another battle in December.

Such a strategy would likely elicit intense blowback from those conservatives who want any increase in the debt limit paired with spending cuts. Senate Majority Leader Mitch McConnell will need to rely on Democrats — as will House Speaker Paul D. Ryan, most likely — to help advance several key measures, giving the minority party potential sway in future negotiations on the U.S. immigration system.

Surrounding all the chaos expected to come with moving through the legislative checklist will be an expanding investigation into possible ties between the Trump campaign and the Russian government, as well as escalating tensions with North Korea.

An unexpected issue

Trump’s decision on Tuesday to end the DACA program — which provides social security numbers and federal benefits to children of undocumented immigrants who qualify — is not making the task of governing any easier for the GOP.

Republicans had no plans to address immigration this year and there is no clear path forward on the effort. The party is also already facing a treacherous next few months in the aftermath of an embarrassing defeat on the effort to repeal and replace the 2010 health care law.

McConnell did not mention the ticking clock on DACA at all on Tuesday when laying out the Senate schedule for September.

Still, despite everything going on, for some Democrats and Republicans, finding a quick solution for the some 800,000 people registered under the DACA program is expected to be paramount. How that comes about, however, remains to be seen. Sen. Lindsey Graham, for example, called legislation he introduced this year with Senate Minority Whip Richard J. Durbin of Illinois to create a path to citizenship for those individuals a “good down payment” for an eventual comprehensive package.

Democratic response

The six-month deadline the Trump administration put on the DACA rollback is sure to linger above all upcoming negotiations for the litany of agenda items before the Senate, as Democrats will likely look to secure protections for those covered under the program without any major upheaval of the current immigration system.

And with no real reason to swallow demands from hard-line Republicans, Democrats could be in a good position to try to achieve just that. While the party could shoulder some blame in the event of a government shutdown or credit default, Republicans control both chambers of Congress and the White House, and culpability would most certainly rest with them.

But there is no clear signal at this point that a stand-alone bill to authorize DACA could even pass Congress if it was put on the calendar. When asked about it Tuesday, Durbin said his legislation with Graham was at a “good, strong starting point.”

While several Republicans say they would support codifying in some way the policy implemented through executive action by former President Barack Obama, the White House has signaled it would need it to be paired with some major changes to the current U.S. immigration system — likely increased border security or funding for a wall on the U.S.-Mexico border.

Democrats and some Senate Republicans are unlikely to go along with that plan. And members are already drawing battle lines to prepare for the fight.

GOP Sen. Thom Tillis of North Carolina, for example, is planning on introducing legislation on the DACA issue next week, according to a statement released Tuesday. Several others, including Arkansas Republican Tom Cotton, released statements opposing a stand-alone bill that would just codify the program into law.

Other work

On top of everything else, Congress is expected to try to reauthorize several other measures, including a popular children’s health insurance program, that expire at the end of the month.

The Senate is also kicking off work this week on a bipartisan health care bill, negotiations that could cause consternation between the two parties and add more turmoil to an already strenuous year.

And with other deadlines mounting, a massive overhaul of the U.S. tax code — a cornerstone of Trump and the GOP’s legislative agenda — seems less of a possibility this year.

Before leaving for the August recess, senators said little work had been done on the effort due to the Republican attempt to overhaul the U.S. health care system. The need for Congress to act now on DACA puts even more pressure on the ambitious timeline GOP leaders put on the tax overhaul initiative.