(NewsNation) — More than 21 million people have already voted and some states are smashing voting records for the upcoming midterm election. Control of the House and Senate could come down to just a few key races, making turnout that much more important for both political parties.

For voters in Pennsylvania, Tuesday is the deadline to request a mail-in or absentee ballot.

Back in 2020, there were 3 million requests for mail-in ballots for the general election. But so far this year, there have only been 1.3 million mail-in ballots requested, and more than 700,000 of them have already been returned.

The most noticeable drop in requests for mail-in ballots has been in the Philadelphia region, where Democrats have a large footprint.

The drop raises concerns about possible low voter turnout next week.

The winner of the Pennsylvania Senate race could determine the balance of power in the Senate, which is why the race is garnering so much of the national spotlight.

In Pennsylvania, Democrats outnumber Republicans by more than half a million among registered voters.

The Senate race between Democrat John Fetterman and Republican Mehmet Oz has turned out to be very close, and turnout will be key.

“Elections are what they are. We’re gonna find out in a couple of weeks what the people want and that’s what democracy is about and you either support democracy or you don’t. You have to accept democracy, win or lose,” Stewart Watson, a Pennsylvania voter, said.

Despite close to a million ballots already being returned, there are still a lot of undecided voters, and many people are shifting back to in-person voting because of concerns about voter security.

That means the candidates still have time to make an impression on those voters.

Fetterman is campaigning heavily in some of the state’s most populous places like Philadelphia, Pittsburgh and Harrisburg where there’s a large Democratic base. He’ll need a strong turnout in those areas.

Oz is banking on the suburbs and central Pennsylvania, where Republicans have a strong following. Both candidates will also need moderate and undecided voters to bolster their chances of winning.