HARRISBURG, Pa. (CBS/AP) — A new lawsuit filed Thursday is challenging Pennsylvania’s court-ordered deadline to count mail-in ballots that are received up to three days after the Nov. 3 election in the presidential battleground state. Plaintiffs — including four registered voters from Somerset County and a Republican congressional candidate — are asking a federal judge in Pittsburgh to block the deadline extension from going into effect.

It names Gov. Tom Wolf’s top election official, Kathy Boockvar, a Democrat who has argued in the state’s courts that a deadline extension was necessary to prevent late-arriving mail-in votes from being thrown out because of postal delays.

The lawsuit comes 12 days before the election and three days after the U.S. Supreme Court, divided 4-4, rejected a Republican plea making a slightly different argument than Thursday’s lawsuit.

Both sought to block a state Supreme Court ruling that required county election officials to receive and count mailed-in ballots that arrive up until Nov. 6, even if they don’t have a clear postmark, as long as there is no proof it was mailed after the polls closed.

Thursday’s lawsuit said that the court’s deadline extension and the lack of a postmark requirement “will allow for late and otherwise unlawful ballots to be counted.”

That is unconstitutionally unfair to in-person voters and exceeded the court’s authority by exercising a power that is constitutionally vested in Congress and the Legislature, the lawsuit said.

With about 2.9 million mail-in ballots requested so far, registered Democrats have requested about 1.1 million more mail-in ballots than Republicans, or 1.8 million to 700,000, according to state data.

The Democratic majority on the state’s high court had cited surging demand for mail-in ballots during the coronavirus pandemic and warnings that postal service delays could invalidate huge numbers of ballots to invoke the power, used previously by the state’s courts, to extend election deadlines during a disaster emergency.

According to the latest CBS News Battleground Tracker, Democratic presidential nominee Joe Biden holds a seven-point lead over President Donald Trump — 53% to 46%.

(© Copyright 2020 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)

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