What will change with Republicans controlling the House of Representatives

As a new session begins, the United States Congress is officially a house divided.

The lower chamber, the House of Representatives, will be held by Republicans, while the 100-seat Senate will be run by Democrats.

The split will significantly affect either party's ability to pass significant legislation through Congress, but particularly Democrats, who also hold the presidency.

The result could be two years of partisan deadlock that may remain unresolved until the next election cycle in 2024.

Fault lines have emerged within the parties themselves. The first day of the new Congress featured a battle among House Republicans over whether to officially choose Representative Kevin McCarthy of California as Speaker of the House.

Here's what you need to know about a divided US Congress and what it means for American governance.

In the House, the Republican party will get to set the legislative agenda and chair all the committees, which deal with issues like oversight, the economy and labour.

In the Senate, Democrats will call the shots on bills and significantly control which legislation comes to the floor for a vote.

Because the House and Senate will be controlled by different parties, this will drastically reduce the major initiatives either party will get to accomplish.

It's also likely to turn necessary functions of Congress, like funding the government or re-authorising certain types of spending, into massive battles as factions within each party use these crucial deadlines for leverage.

Each party controls their chamber by the thinnest of margins. That means individual members will have more power to influence or block legislation they don't like, especially if they band together with like-minded politicians.

The first day of the new session featured a protracted Republican battle to choose their leader, who will serve as the speaker of the House of Representatives. Expect even more intra-party squabbles for the next two years.

House Republicans have also said they would use their control of committees to investigate Joe Biden and his son, Hunter Biden. Marjorie Taylor Greene, a right-wing congresswoman from Georgia, has called for the House Republicans to impeach Mr Biden, as the Democrats twice did to Donald Trump.

Mr McCarthy is also negotiating with members of his caucus who want to change some procedural aspects of how the House of Representatives functions, in exchange for their votes for his speakership.

Republican control of the House will spell the end of the House committee that is investigating Mr Trump's role in the 6 January 2021 attack on the US Capitol, when a horde of his supporters stormed Congress after Mr Trump made baseless claims of election fraud.

Shortly before the midterm elections, the committee issued a subpoena to Mr Trump with which he's not expected to comply.

The current House Republican leader Kevin McCarthy has called the Capitol riot committee "the most political and least legitimate committee in American history", and all but two Republicans refused to participate.

President Joe Biden will now face the herculean task of passing any initiatives through a House of Representatives controlled by the opposing party with an influential bloc of right-wing members.

For the first two years of his presidency, Mr Biden's party had control of both chambers of Congress. His path to passing major priorities like climate change legislation was often rocky, but ultimately, Democrats were able to marshal votes and succeed with big-ticket items.

But now, Mr Biden has lost one chamber to the opposition party, which will not be inclined to give him major victories heading into a presidential election cycle.

It will make it all the more difficult for Mr Biden to accomplish big priorities for the next two years.