The special election in Pennsylvania’s 18th Congressional District between Democrat Conor Lamb and Republican Rick Saccone is tight. Election watchers are starting to speculate that it may not be called Tuesday night at all and could even be headed for a recount.

As of 10:30 pm Tuesday, the race was still too close to call. Lamb was at 49.8 percent and Saccone was at 49.6 percent, with 98 percent of precincts reporting.

Right now there’s a possibility that there could be a recount, although it likely would not happen for the next few days.

How does a Pennsylvania recount work?

Under Pennsylvania state law, if one candidate wins an election by less than half of a percentage point, all counties must start a recount.

But there’s a catch — PA-18 is an election for just one district, not the entire state. That means no mandatory recount is triggered, according to the Pennsylvania secretary of state’s office.

Petitions to have a recount are allowed, and voters have five days to file them, according to CNN’s David Wright.

Pennsylvania Sec. of State spokesperson Wanda Murren tells CNN that b/c this is a district race & not statewide, there is no mandatory recount here. Petitions are allowed, which require 3 voters in each precinct; have 5 days to file after the county completes its computation. — David Wright (@DavidWright_CNN) March 14, 2018

If a recount were to happen, it wouldn’t be for a few days, according to Pennsylvania election lawyer Adam Bonin.

If I have to, I'll explain. Promise. But the first important thing to know is that this is not a count tonight; it's unofficial and does not include absentee or provisional ballots. The formal count begins Friday, & overseas/military absentees have until next Tues to come in. https://t.co/M43ENosfZk — Adam Bonin (@adambonin) March 14, 2018

Back in 2016, the state was requested to start a recount by the Green Party’s Jill Stein after the 2016 presidential election, to make sure none of the state’s electronic voting equipment was tampered with (the request was denied by a judge).

Pennsylvania’s voting machines are fairly outdated, and last month, Gov. Tom Wolf, a Democrat, ordered that the state replace its old voting machines with newer ones that can leave a paper trail, as a safeguard against hacking. It would cost about $60 million to replace all of them, according to the website Engadget.

But Wolf’s operating budget didn’t include any money for the new machines, which means a lot of counties are still operating with the old ones.

This is an extremely tight race — which is bad for Republicans

On its face, Tuesday’s special congressional election in the southwest corner of Pennsylvania was supposed to be a breeze for the GOP, which has held this seat since 2003. The Cook Political Report rates the district R+11 (due in part to partisan gerrymandering that the state Supreme Court recently ruled unconstitutional).

But now it’s looking like Lamb is in a dead heat with Saccone. Last week, the Cook Political Report declared the race a toss-up, moving it away from its previous “lean Republican” rating.

Saccone was supposed to walk away with a win in a district Trump won by 20 points in 2016. The fact that he could lose it by a hair is bad, but even if he pulls out a win by a fraction, pollsters agree it’s still a bad sign for GOP chances in 2018.