Half a million Pennsylvania residents woke up without power on Thursday morning, injecting fresh uncertainty into what Election Day will bring for the battleground state.

More than 500,000 Pennsylvanians were still in the dark as of 8:00 a.m. on Thursday, according to a spokesperson for the Pennsylvania Public Utility Commission. By that measurement, Hurricane Sandy has battered Pennsylvania more than any other swing state: In Ohio, by contrast, the number of power outages was hovering around 100,000.

With the election less than a week away, the ongoing blackouts could discourage voters from heading to the polls. Studies have shown that inclement weather tends to suppress overall turnout and is more likely to help Republicans as potential Democratic voters stay home.

The stakes are particularly high in Pennsylvania, a perennial swing state with 20 electoral votes. Republican nominee Mitt Romney has launched a fresh volley of ads in Pennsylvania after having pulled advertisements there in September, signaling the campaign's renewed confidence that it can win the state.

Pennsylvania has already seen a pitched election-year battle over access to the polls. Democrats and voting rights groups sued to block a new state law that required voters to present government-issued photo identification before being allowed to cast ballots.

While Republicans proponents defended the measure as a safeguard against voting fraud, critics argued that it would disenfranchise Pennsylvanians, like minority and low-income voters, who are more likely to lack photo ID and to lean toward Democratic candidates. A federal judge recently vindicated opponents of the voter ID law, blocking the measure from going into effect before Election Day.

But Sandy's fury has placed another obstacle between voters and the ballot box. Pennsylvanians worried about sifting through storm damage and getting their power restored will be less likely to make voting a priority, although much will hinge on how many Pennsylvanians have power restored by next Tuesday.

The consequences for Pennsylvania are blunted by the fact that the state does not offer residents the ability to vote before Election Day. In Maryland, by contrast, officials have reinstated early voting after suspending it for Sandy.

Given how invested many voters appear to be in this election, Sandy's aftermath is likely to have a "minimal effect" as lights flicker back on, according to University of Pennsylvania Political Science Professor Marc Meredith.

“There's certainly a possibility that [the storm] could affect some marginal voters," Meredith said, "but I think the people who are really excited about voting in a presidential election will do it even without power. “Come next Tuesday things will largely be back to usual.”