The political world has known for a while that Republican Rep. Bill Johnson of Ohio was prepared to step down from Capitol Hill to become president of Youngstown State University, but there was some uncertainty about his timing. As Politico reported, those details have now come into focus.

Ohio GOP Rep. Bill Johnson will resign from Congress on Jan. 21 to become the new head of Youngstown State University, a move that will further shrink the tight House GOP majority. … “Bill submitted his official resignation from Congress today, effective at the end of day on January 21, 2024, paving the way for him to begin his presidency this month,” Michael Peterson, chair of the school’s board of trustees, wrote in a message to the university community.

To be sure, there’s been some controversy surrounding Johnson’s selection. The Vindicator, the daily newspaper in the Youngstown area, reported that the university’s decision to elevate the GOP congressman “was met with vocal criticism from faculty, students, alumni and donors who objected to the confidential search as well as the decision to hire Johnson because of his politics and lack of experience in higher education.”

But for Johnson’s colleagues in the House Republican conference, there’s an entirely different problem to consider: Just how small will the GOP majority in the chamber become?

In general, the legislative arithmetic is relatively straightforward: There are 435 seats in the House, which means 218 seats is the bare minimum for a majority. When the current Congress began early last year, Republicans started with 222 seats — which meant on any given vote, GOP leaders could lose no more than four of their own members.

That number has grown progressively smaller. A month ago, members took the extraordinary step of expelling former Republican Rep. George Santos, which left the GOP conference with 221 members. Earlier this week, former Republican House Speaker Kevin McCarthy ended his congressional career, shrinking the House GOP’s total to 220 members.

When Ohio’s Johnson leaves for Youngstown State University later this month, that will leave House Republicans with just 219 members.

GOP leaders spent much of 2023 struggling to pass their own proposals. In the coming weeks, their task will become even more difficult.

To be sure, there will soon be some special elections, which will give the party opportunities to replenish their ranks. But (a) there are no guarantees that Republicans will prevail in these races, especially as Democrats try to flip Santos’ New York district; (b) those special elections are not imminent, leaving GOP leaders in a bind with some important votes coming up this month; and (c) even when those races are over, Republicans will likely find themselves in the same mess they were in last year, operating with a tiny majority filled with members who don’t want to compromise on their far-right vision, even as Democrats control the Senate and the White House.

While we’re at it, let’s also not overlook the recent chatter about possibly trying to expel Republican Rep. Matt Gaetz of Florida, which at least in theory might shrink the party’s majority yet again.

Watch this space.