It could take days — or weeks — to find out which party won Congress

The political world is waiting with bated breath to see whether Democrats can retake the House and the Senate on election night.

But it could take days — or even weeks — before we learn who won either chamber.

Key races that could determine control of each chamber might be close enough to drag out over the following days, even meriting recounts (and the inevitable legal battles that come with them).

The infamous 2000 Florida presidential recount took more than a month and a Supreme Court ruling before George W. Bush was declared to have won the presidency. Al Franken’s first Senate race in 2008 took even longer to be resolved — about eight months passed after the election before he was sworn into the Senate.

Chris Hondros/Newsmakers

Another problem is that some states just count votes really slowly — often because they have to verify a plethora of mail ballots sent in at the last minute. And there are more than a dozen key House races in states like these, most notably in California, an infamously slow-counting state with at least seven highly competitive races.

So if the contests in the House or Senate are close enough, we might have to wait. But such delays would play out differently for each chamber.

The Senate drama scenarios

Because of the particular races that are up in the Senate this year (only nine Republican-held seats compared to 26 Democratic-held ones), a Democratic landslide isn’t a realistic possibility here. Either the chamber will be determined by a narrow margin or there will be a Republican blowout because of several defeats of Democratic incumbents in red states.

We’ll get some signs about whether a red wave is in the cards for the Senate quickly, as polls close in races for Democratic Sens. Joe Donnelly (IN), Joe Manchin (WV), and Claire McCaskill (MO) relatively early in the night. If these Democratic incumbents in deeply conservative states do well, the party will have a good chance of avoiding a total blowout.

Scott Olson/Getty Images

Then to see whether a Democratic takeover is a possibility, look at the GOP-held races in Texas and Tennessee. Democrats almost surely need to win one of these to get a majority. Votes from the other GOP-held targets Arizona and Nevada will come in a bit later.

But if we don’t know who won the majority on election night, it will likely be for one or more of these reasons:

1) Slow counting and close races: During the closely fought battle for the Senate of 2006, there were two races — Virginia and Montana — that weren’t called until Wednesday. Democrats won both narrowly, which gave them the exact number of seats they needed for a majority: 51. But that year, we did not know which party would control the Senate by the end of election night.

Then in 2012, Democrats locked up their majority by winning enough races to have 53 seats on election night. But by 2:30 am Eastern there were still three races that weren’t called — Montana again, as well as Nevada (Dean Heller’s seat) and North Dakota (Heidi Heitkamp’s). They ended up all being resolved by midday Wednesday.

That same group of Senate seats from 2006 and 2012 is up again this year. Of course, we don’t know which races will happen to be close this time around when the votes come in. But there are many races in states where polls close late that have been known to count slowly.

2) The Mississippi runoff: Mississippi’s special Senate election could be another problem. There was no primary for this election, so Tuesday’s voting will be for a so-called jungle primary. The major candidates are two Republicans — the appointed incumbent, Cindy Hyde-Smith, and conservative Chris McDaniel — and one Democrat, Mike Espy.

If one of these candidates wins more than 50 percent of the vote Tuesday, he or she will win the Senate seat outright. However, if no one tops that threshold (as a recent poll suggests is likely), the first- and second-place candidates win spots in a runoff election on November 27, 2018. So we may not know which party will hold this seat until then. (Of course, Mississippi is a deeply conservative state, and whichever Republican makes it through would be favored to win ... but still, weird things can happen.)

3) A recount that would determine the majority: Back in 2008, only a few hundred votes separated Al Franken from his GOP opponent in Minnesota’s 2008 Senate election. The recount and an ensuing legal battle stretched on for months, ensuring Franken wasn’t seated until July 2009.

Now, that year, Democrats had a large majority in the Senate, so partisan control didn’t hang in the balance all those months. But FiveThirtyEight’s model estimates around a 24 percent chance that this year’s Senate will be decided by a single race (that either Democrats will end up with a 51-49 majority or Republicans will control a 50-50 chamber because of Vice President Mike Pence’s tie-breaking vote).

So it’s certainly possible that once the dust settles from the election night races and Mississippi this time around, the called races could give us a Senate of 50 Democrats and 49 Republicans, with the one other race — the one that would determine party control — bogged down in recount and legal limbo.

Considering the enormous stakes of Senate control — there could be one or more Supreme Court vacancies in the next few years, and many of Trump’s other judicial and executive branch nominees will have to be confirmed — another Franken-esque recount is bound to lead to a massively expensive and ugly legal battle.

The House drama scenario

Unlike the Senate, a blue tsunami for Democrats in the House is a distinct possibility — and if it’s happening, that will probably become clear early.

Already by 8 pm Eastern, polls in a fairly broad cross-section of regions and swing districts will have closed. As these votes get counted, we’ll get a sense of what happened in both suburban and working-class-heavy districts in the Northeast (New Jersey, Pennsylvania), the Midwest (Ohio), and the Southern swing states (Virginia, North Carolina, Georgia, Florida). We’ll be able to get a sense of, for example, how districts that voted for Hillary Clinton are tipping, compared to districts Trump won big or to districts Obama won but then flipped to Trump.

Julia Rendleman for the Washington Post

If Democrats are cleaning up across the board at this point, quickly winning many Toss-Up and Lean Republican races that vary in their demographic and partisan makeup, it will be clear they’re headed for a House takeover.

But if many of those key races are instead extremely close or tip toward Republicans, settle in for a long night. The Upshot’s Nate Cohn has tweeted that if the polls the Upshot has conducted with Siena College were to be exactly spot-on, House control could “take weeks to decide.”

The likely reason is slightly different than for the Senate. Since there are 435 seats up in the House, compared to just 35 in the Senate, it’s far less likely that a single House race recount will determine control of the chamber. FiveThirtyEight estimates a less than 4 percent chance the House will end up with a one-seat difference between the parties, compared to a 24 percent or so chance for the Senate.

Instead, what would most likely hold things up is slow counting of mail ballots. A few states use only a vote-by-mail system, and several others make it so easy to vote absentee by mail that much of their electorates chose to do so rather than voting in person. And some states have committed to counting ballots that show up days later, so long as they are postmarked by Election Day.

Yet counting mail ballots takes longer than counting in-person votes. That’s because before they can be counted, each voter’s information has to be verified according to the voter registration list and with a signature check, to prevent fraud. (For ballots cast in person, that information has already been verified by election night — it was done when the person showed up to vote.)

If mail ballots are sent in early, that verification can be done before election night. But, of course, voters tend to procrastinate until the last minute, meaning elections offices usually get a huge pile of new ballots dumped on them on election night (and in some states, afterward) that suddenly have to be verified.

In 2016, it took a month for California to count its primary votes. Washington state, Utah, and Alaska have bemoaned slow vote counting in the past too — and they all extensively use mail voting. There are more than a dozen House races that look competitive in these states.

So if the contest for House seats between the parties turns out to be close, and key races in states with lots of mail voting are also close, we could be waiting for quite some time before we know who controls the House.

Robyn Beck/AFP/Getty Images

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