As votes continue to be counted, Pennsylvania has emerged as a key battleground state in this year’s election. Up for grabs: the commonwealth’s 20 electoral votes, which could help either candidate clinch a victory.

And some readers have reached out wondering how those electoral votes are allocated.

“Can electoral votes be cast proportionally, reflecting the popular vote in each state?” one reader wrote in to Curious Philly. “Is this a federal decision, or do states decide?”

So can Pennsylvania split up its electoral votes, giving some to President Donald Trump, and others to former Vice President Joe Biden? Here is what you need to know:

Can Pennsylvania split its 20 electoral votes?

In a word, no — or at least not currently.

Pennsylvania is what is known as a “winner-take-all” state, meaning that all of our electoral votes go to whichever candidate wins the popular vote in the commonwealth. In Pennsylvania, each campaign chooses their slate of electors, and the electors for the candidate that wins the popular vote in the state then cast their votes for president and vice president.

Each state can determine their own Electoral College systems, according to the National Archives and Records Administration. But overall, 48 states (plus Washington) follow the winner-take-all format.

What do other states do?

The two states that don’t adhere to the winner-take-all format are Maine (four electoral votes) and Nebraska (five electoral votes), which both use the “congressional district method” to split their electoral votes, which they have done for decades.

Rather than give all of their electoral votes to a single candidate, both states allocate electoral votes based on the winner of the popular vote in each congressional district. According to FairVote.org, a nonpartisan electoral reform group, this means that the winner of each district gets one electoral vote, and the statewide popular vote winner gets two additional electoral votes.

Could we abandon the “winner-take-all” plan?

We could eventually, though it’s not currently likely. The last major push to move away from the winner-take-all system in Pennsylvania was in 2011, when then-Senate Majority leader Dominic Pileggi (R., Delaware) proposed that the state use a congressional district plan. He floated a similar plan in 2013.

Pileggi’s proposal was similar to how Maine and Nebraska allocate electoral votes, giving two of Pennsylvania’s electors to the winner of the statewide vote, and dividing the other 18 based on the vote in each congressional district. In a 2011 Inquirer op-ed, Pileggi said it was an “easy-to-understand, commonsense way to achieve … strengthening the role of individual voters.”

Critics such as Franklin & Marshall College political scientist Terry Madonna, however, said the change would “reduce voter turnout and end Pennsylvania’s status as a battleground state.” Others, like Sen. Anthony H. Williams (D., Phila.), reportedly said the plan would “disproportionately affect the value of votes” in Philadelphia.