As I write this, there may or may not be a second impeachment vote happening later today in the House of Representatives. Republicans tried to impeach the secretary of the Department of Homeland Defense last week and suffered a rather embarrassing loss, so one would assume that this time around the speaker will do a better job of counting noses before the vote takes place -- and also that this time the vote won't happen if Republicans don't have enough. As we saw last week, the difference of one vote can indeed be critical in such a closely-divided House.

So I thought today was a good day to do some nose-counting math in general over in the House, since the political world is also awaiting the results of a special election in New York to fill the seat of George Santos (or whatever he's calling himself today). The seat could easily flip back to the Democrats, but the polling shows a very close race (and Long Island has been hit with a snowstorm on Election Day, which could dramatically affect the turnout for in-person voting).

As the House sits right now, there are 431 members and four vacancies. There is the Santos seat, and then there are the seats of Kevin McCarthy and Bill Johnson (two Republicans who recently resigned mid-term), as well as the seat of Brian Higgins (a Democrat who also just stepped down). With these four seats vacant, here is the current partisan breakdown of the House:

219 -- Republican

212 -- Democratic

4 -- Vacant

This means that if everyone is present and voting, Speaker Mike Johnson can afford to lose three of his fellow Republicans and still muster a majority (216-215). The problem for Johnson last week was that he thought there would be one Republican and one Democrat absent for medical reasons, but the Democrat surprised everyone by showing up (after taking an Uber over to the Capitol from his hospital bed). So Johnson lost three Republican votes who crossed the aisle and voted with the Democrats against impeachment, but he was down one vote on his side while every Democrat showed up to vote. So the functional impeachment vote was 215-215 (until one Republican changed their vote for parliamentary reasons -- but the actual nose-counting wound up a tie, and ties don't win in the House).

The Republican who was absent last week is now back in Washington after his doctors cleared him for travel. Which is why Johnson is scheduling the re-vote for tonight. If everyone shows up, he should now have a 216-215 majority. But that snowstorm also hit D.C., so some members may find it impossible to travel and wind up being absent tonight.

However, as mentioned, tonight will also feature the returns from the New York special election. If it is a clear victory either way, then the representative-elect could be quickly sworn in and shift the balance of power. So let's take a look at the two possible outcomes. If the Republican wins, the House balance of power will look like this:

220 -- Republican

212 -- Democratic

3 -- Vacant

This won't change the calculus for Johnson, because he will still only be able to lose 3 votes across the aisle. This would leave a 217-215 majority, but losing four votes would leave a tie at 216. About the only thing Johnson will gain by winning the special election would be to have a buffer of one member who could be absent for a vote while still being able to muster a majority. This, obviously, is what did him in before, so it would allow him at least a tiny amount of breathing room.

But if the Democrat wins, the calculus does indeed shift:

219 -- Republican

213 -- Democratic

3 -- Vacant

That would mean that Johnson could then only afford to lose two votes, since if he lost three it would wind up tied at 216 again. An already-razor-thin majority for the GOP would get one vote closer, in other words. This is why the Democrats are fighting so hard to retake Santos's seat.

But even if they do, the situation will change again within the next few months. Those other three vacancies will all see special elections of their own, and all three districts are pretty safe ones -- meaning the final tally will almost certainly wind up with two more Republicans and one more Democrat. A Democrat does have an outside chance at flipping Kevin McCarthy's seat in California's Central Valley, but it's a longshot at best.

Without adding in tonight's special election, here's how this will leave the count:

221 -- Republican

213 -- Democratic

1 -- Vacancy (tonight's special election)

This leaves the balance at three again -- Johnson could afford to lose three votes and have a majority (even with one absence), while losing four would leave him with a 217-217 tie.

This is also why tonight's election is important. Because if the Democrats win, the balance will wind up (with no vacancies at all) at:

221 -- Republican

214 -- Democratic

Which means once again that Johnson can only lose three votes and still prevail. But if the Republican wins it would mean a count of:

222 -- Republican

213 -- Democratic

This would make Johnson's job easier by one more vote, because now he'd be able to lose four seats and still win the day on any vote.

With the House majority closer than ever, each individual vote matters a lot. In the normal course of things, the number and makeup of the House undergoes some natural "churn," as people resign, die in office, get hit with major medical problems that bench them for a while, or (in the case of Santos) get unceremoniously chucked out. When the margin of the majority is a comfortable one (in the double digits, say...) then losing a member here and there for whatever reason isn't a crisis. But Republicans have never had a comfortable majority in the current Congress, and the margin is so close that every vote does indeed matter a lot more.

The balance of power is so close in the House that Democrats have a decent shot of regaining control of the chamber this November just through redistricting alone. Several states have changed their district maps since the last election (most through being forced to by the courts), and this could wind up determining the balance of power, even absent a big Democratic "wave" election.

But we've got plenty of time to hash all that out before November. For now -- as we await the New York special election returns and see whether the House is going to impeach the first cabinet member in almost 150 years -- we just wanted everyone to know exactly what is at stake, in terms of the Republican majority (at least until the next special election is held).

-- Chris Weigant

Follow Chris on Twitter: @ChrisWeigant