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House Speaker Mike Johnson speaks during a news conference at the US Capitol December 5 in Washington, DC.

Speaker Mike Johnson is facing an extremely narrow majority in the House and tough vote math as Congress confronts upcoming battles over government funding, aid to Ukraine and Israel and border security.

At the start of the new year, Republicans control just 220 seats while Democrats control 213, which means the House GOP can’t afford to lose more than a few votes to pass party-line priorities. Additionally, House Majority Leader Steve Scalise’s office has announced that he will work remotely until returning to Washington in February as he recovers from a stem cell transplant.

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The House Republican majority will shrink even further by the end of the month with Ohio GOP Rep. Bill Johnson resigning from Congress on January 21 to take a new job as president of Youngstown State University. At that point, Republicans will control 219 seats to 213 for Democrats.

There are currently two vacancies in the House following former Speaker Kevin McCarthy’s resignation from Congress at the end of last year and the expulsion of former GOP Rep. George Santos of New York.

Johnson will have little margin for error as Congress faces major policy battles in the weeks ahead.

The most pressing issues are a pair of government shutdown deadlines in January and February and a high-stakes effort to strike a deal over border security and aid for Ukraine and Israel. It’s far from clear, however, whether lawmakers will be able to reach consensus over border security and foreign aid and legislation to avert a shutdown.

In a rare event, Congress faces not one but two government shutdown deadlines early in the new year – on January 19 and February 2.

Congress passed stopgap legislation in mid-November extending government funding until January 19 for priorities including military construction, veterans’ affairs, transportation, housing and the Energy Department. The rest of the government will be funded until February 2.

There are growing threats, however, from some House Republicans to shut down the government over issues at the southern border if hardline conservative border policies are not adopted.

Hardline House conservatives have already shown that they can hold major sway in the chamber with such a narrow majority – most notably when a group of hardliners moved to oust McCarthy from the speakership in a historic and unprecedented vote last year.

The exact size and scope of the far right of the House Republican Conference varies from issue to issue. Last week, Senate Majority Leader Chuck Schumer criticized House conservatives, describing “the 30 of them” in an apparent reference to conservatives who have made hardline demands over border policy, though it’s unclear exactly which lawmakers Schumer was citing.

Another key group within the House GOP conference are politically vulnerable members from battleground districts – members who will be under intense scrutiny during the 2024 election year.

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There were 18 Republicans in House districts that President Joe Biden won in 2020 – a number that is now down to 17 after the expulsion of Santos. The fate of these politically vulnerable members will be key to whether the GOP can hold onto its majority.

Johnson will have to balance competing demands from the far-right and more moderate factions of the conference, no easy task as Congress faces government shutdown battles and fights over hot-button issues that have long been contentious on Capitol Hill such as border security.