Republicans officially captured control of the House on Wednesday, as the Associated Press called the 218th seat for the party. The House victory ends four years of Democratic control of the lower chamber, handing Republicans the speakership and the chairmanships of key committees, while Democrats will maintain control of the Senate.

But the incoming Republican speaker has the unenviable task of attempting to pass legislation with a very narrow majority, where only a few defections within the party will be enough to kill a bill.

Republicans had hoped that a “red wave” in the midterm elections would allow them to flip dozens of House seats, giving them a much more comfortable majority. Instead, Republicans were barely about to flip the House, and Democrats may even be able to increase their Senate majority depending on the results of the Georgia runoff next month.

With the House and the Senate now both called, Washington is bracing for at least two years of split control of Congress. Here’s what we can expect. :

Will Congress be able to pass any bills?

It will be extremely difficult for Democrats to advance their legislative agenda. Republicans can use their majority power to block any bills passed by the Democratic Senate from even getting a vote on the House floor.

Since Joe Biden took office, some notable bills have passed the House with bipartisan support, including the infrastructure law that the president signed late last year. But the new Republican speaker will probably be hesitant to hand Biden and his party any more policy wins before the 2024 presidential race, which could result in a legislative logjam.

How will Republicans use their House majority?

Given their very narrow majority, House Republicans may have trouble advancing major legislation through the chamber. Even if they are able to pass something, the bill would almost certainly fail in the Democratic Senate, so it seems likely House Republicans will focus most of their attention on investigations and executive oversight.

Even before polls closed last Tuesday, House Republicans had outlined plans to launch a series of investigations into the Biden administration and members of the president’s family. Republican members have expressed keen interest in investigating the administration’s handling of the US troop withdrawal from Afghanistan, Biden’s oversight of the US-Mexican border and his son Hunter’s overseas business dealings.

Some of the far-right members of the House Republican caucus have also threatened to use their new majority to hold up must-pass bills, including a debt ceiling hike. If the debt ceiling – essentially, the maximum amount the US government can borrow – is not raised, it could jeopardize the entire US economy. Some House Republicans have signaled they want to withhold support for a debt ceiling increase until they secure concessions on government spending and entitlement programs.

The new House Republican majority could also threaten proposals to send more military aid to Ukraine amidst its war against Russia. The far-right congresswoman Marjorie Taylor Greene has said that “not another penny will go to Ukraine” once Republicans take control, alarming Ukraine’s allies on Capitol Hill and abroad. With such a narrow majority, it only takes a few votes to block bills.

Who will replace Nancy Pelosi as House speaker?

That is a question that many House Republicans are asking themselves right now as well. The obvious frontrunner for the role – which oversees, manages and directs the majority party in the House – is Kevin McCarthy, the California Republican who has served as House minority leader since 2019.

But McCarthy has faced some dissent from within his own caucus, and it remains unclear whether he can get the 218 votes needed to become speaker. On Tuesday, the House Republican caucus easily nominated McCarthy as their speaker candidate, but 31 members cast ballots for the far-right Arizona lawmaker Andy Biggs. That tally could spell disaster for McCarthy when the full floor vote is held in January.

“My position remains the same until further notice – no one has 218 (or close, as needed),” Chip Roy, a member of the far-right Freedom Caucus who nominated Biggs, told the Texas Tribune on Tuesday. “We have to sit down and establish the fundamental changes needed.”

How will Biden work with the new Republican speaker?

Before becoming president, Biden built a reputation in the Senate for his ability to reach across the aisle and strike compromise with his Republican colleagues. During the 2020 Democratic primary, Biden boasted about how he was even able to work with hardline segregationists such as James Eastland and Strom Thurmond. Those comments, meant to demonstrate Biden’s collaborative nature, outraged many Democratic primary voters.

But in recent months, Biden has become increasingly vocal in his criticism of the modern Republican party, which he says is beholden to Donald Trump and hostile to democratic principles. “Donald Trump and the Maga Republicans represent an extremism that threatens the very foundations of our republic,” Biden said in September.

McCarthy has responded to Biden’s criticism by accusing the president of having “chosen to divide, demean, and disparage his fellow Americans … simply because they disagree with his policies”.

So if McCarthy does manage to capture the speakership, he and Biden will not be starting off their new relationship on the best footing. When a reporter asked Biden last week about his relationship with McCarthy, the president deflected.

“I think he’s the Republican leader, and I haven’t had much of [an] occasion to talk to him,” Biden replied. “But I will be talking to him.”

What can Democrats get done without control of the House?

Democrats’ continued control of the Senate ensures that they will still be able to approve Biden’s cabinet and judicial nominations. Their Senate majority will allow Democrats to install more liberal judges in key posts, and it could give them the ability to fill another supreme court seat if one opens up in the next two years.

But overall, Democrats’ best opportunity to enact change between now and 2024 may come down to the power of the executive. Biden has already signed more than 100 executive orders since becoming president, according to the Presidency Project at University of California Santa Barbara.

Biden has used executive orders to overturn some of Trump’s most controversial policies, such as halting funding for construction of a wall at the US-Mexican border, and to advance progressive proposals that would otherwise stall in Congress. Biden’s order to provide student debt relief of up to $20,000 for millions of borrowers was celebrated by the president’s progressive allies, although the policy is now facing legal challenges.

With Republicans now in control of the House, Biden could soon be reaching for his executive pen more frequently.