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FIRST ON FOX — Senior Republican Party officials announced Monday that they are filing 12 lawsuits in Pennsylvania as part of an ongoing effort to "aggressively" defend their pickup in the closely watched Keystone State Senate race.

Speaking to reporters on a call Monday, GOP officials said they have been working closely with Republican candidate Dave McCormick's campaign in an effort to protect his Senate win over three-term incumbent Democrat Sen. Bob Casey, who has refused to concede defeat and has secured a statewide recount.

Both national and state Republican parties have filed lawsuits in four counties across Pennsylvania, urging the courts to not count mail-in ballots with either incorrect or missing dates, in accordance with a Pennsylvania Supreme Court ruling this month.

Republicans noted the defiance they've encountered from some county Democratic leaders, including in Philadelphia, Bucks County, Center County and Delaware County, areas where the GOP focused its first wave of lawsuits. 

"Democrat officials are on video saying that they're going to choose to break the law, and there will be legal consequences for that," a senior party official told Fox News. 

But a lawsuit brought by a GOP candidate over the voting equipment in Delaware County was dismissed last month by the Delaware County Court of Common Pleas as "frivolous." Delaware County Board of Elections officials said in a statement that it was "completely false" to suggest it had not complied with all state Supreme Court orders.

"Delaware County has followed the Pennsylvania Supreme Court order since that order was issued the first time in November 2022 and has NOT processed or counted any ballots from envelopes that were undated or incorrectly dated at any election since that order was issued," the statement said.

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Bob Casey closeup shot

Senator Bob Casey (Mark Makela/Getty Images/File)

In addition to these lawsuits, party officials told Fox News on Monday that they are filing eight additional court challenges in Pennsylvania. The efforts are aimed at ensuring McCormick's victory is upheld and confirming that only legal votes are counted.

The Pennsylvania Supreme Court ruled before the election that mail-in ballots lacking formally required signatures or dates should not be included in official results.

But Democrat officials in Philadelphia and other parts of the state, including Bucks County, Centre County and Montgomery County, have not complied with that order, RNC officials said, prompting the litigation.

Speaking to reporters on a call Monday, Republican Party Chair Michael Whatley said senior RNC officials have been "coordinating closely with Dave McCormick's campaign to ensure that this hard won Senate seat will be protected."

He also vowed to maintain "an aggressive, comprehensive and strategic legal posture for as long as it takes to ensure that this election is going to be certified" in Pennsylvania.

"The RNC and the Republican Party of Pennsylvania are aggressively fighting back to bring an end to this corrupt and despicable conduct" in the state, Whatley said. 

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Dave McCormick speaking with Donald Trump behind him

Republican presidential candidate Donald Trump listens as U.S. Senate candidate Dave McCormick speaks during a campaign rally in Reading, Pa., on Nov. 4, 2024. (Ed Jones/AFP via Getty Images)

McCormick's unofficial margin of victory stands at roughly 17,000 votes, or within the 0.5% threshold required under Pennsylvania law to trigger an automatic recount.

But RNC officials challenged the notion that the Senate recount, which continues through Nov. 26, will change the outcome in any substantive way. They have decried the effort, which costs an estimated $1 million, as a waste of taxpayer money, noting that since 2000 there have been just three statewide election recounts in Pennsylvania, and each has resulted in an average change of 393 votes.

In a "worst-case" scenario, they said, the uncounted provisional, mail-in and absentee ballots could reduce McCormick's margin of victory "to maybe 14,000" votes.

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Trump rally crowd shot

(Matthew McDermott for Fox News Digital/File)

National and state Republican officials said they have deployed "hundreds of attorneys and other observers" on the ground at recount sites in "every county in Pennsylvania" to ensure the process is conducted freely and fairly.

Speaking to reporters Monday, Pennsylvania Republican Party Chair Lawrence Tabas took aim at the price of the recount, which is estimated to be around $1 million.

He also criticized possible political ramifications of the recount, which he said threatened to erode voter confidence in the election system.

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This has been a frequent claim repeated by Republicans as they seek to challenge the recount.

"The Casey campaign could end the recount at any time," Tabas said. "And there are political ramifications of eroding the voters' confidence in elections that has been built. So we need to stop this attempt at electioneering and declare McCormick the winner."

"There's no mathematical way to achieve what the Casey folks apparently think they can achieve," he said.