David McCormick speaks during an election night party in Pittsburgh, Pennsylvania, on Tuesday, May 17, 2022.
CNN  — 

Dave McCormick’s campaign filed a lawsuit Monday evening to have all undated ballots counted in Pennsylvania’s too-close-to-call Senate primary race, where he is currently narrowly trailing Republican rival Mehmet Oz.

The move triggered action from the Republican National Committee, which decided to intervene on the lawsuit and ask the court not to allow undated ballots from being counted. While the move puts the Republican committee on Oz’s side and against McCormick, a committee aide tells CNN that they would be happy with either candidate winning, and their intervention is consistent with their position that undated ballots should not be counted.

“We certainly do not think ballots without dates should be counted, because how do you know when they came in?” RNC chair Ronna McDaniel said Sunday on Fox News. “I think that is common sense and that is definitely where the RNC and the GOP is.”

The lawsuit is seeking to force all 67 counties to count ballots that were received on time but submitted without a hand-written date on the envelope, citing a recent court ruling related to a local election from November 2021. A federal appeals court in Philadelphia ruled Friday that all ballots submitted without a date should be counted in a local race for a county judgeship.

“Both the Pennsylvania Supreme Court and the United States Court of Appeals for the Third Circuit have held that mail-in ballots should not be disqualified simply because the voters failed to hand write a date on the exterior mailing envelope of their ballots,” Chuck Cooper, chief legal counsel for McCormick’s campaign, said in a statement.

“Because all ballots are time-stamped by the County Boards of Elections on receipt, a voter’s handwritten date is meaningless. All timely ballots of qualified Republican voters should be counted.”

Oz – who is backed by former President Donald Trump and leads McCormick by just 983 votes as of Tuesday morning – is fighting back against McCormick’s effort to have undated ballots counted.

Oz’s campaign manager, Casey Contres, accused McCormick’s legal team of using a Democratic playbook and warned it could have “long term harmful consequences for our elections in the Commonwealth of Pennsylvania.”

His campaign has also swatted down the idea that this would change the outcome of the election.

“Dr. Mehmet Oz continues to respectfully allow Pennsylvania’s vote counting process to take place and puts his faith in the Republican voters who we believe have chosen him as their nominee,” Contres said in a statement over the weekend, before the lawsuit was filed. “That is why our campaign will oppose the McCormick legal team’s request that election boards ignore both Pennsylvania Supreme Court and state election law and accept legally rejected ballots.”

Matt Raymer, chief counsel for the Republican National Committee, told CNN in a statement that the group is intervening “because election laws are meant to be followed and changing the rules when ballots are already being counted harms the integrity of our elections.”

“Either of Pennsylvania’s leading Republican Senate candidates would represent the Keystone State better than a Democrat, but Pennsylvania law is clear that undated absentee ballots may not be counted,” he said. “This is another example of the RNC’s ironclad commitment to ensuring that the highest standards of transparency and security are upheld throughout the election process.”

Race likely headed to recount

Pennsylvania’s Department of State, which praised the federal appeals court ruling, said it was working to determine how many undated ballots there were from last Tuesday’s election. The race is likely headed to a recount, which is automatically triggered if the race’s vote margin is within half a percentage point.

Jonathan Marks, Pennsylvania deputy secretary for elections and commissions, told CNN on Tuesday that while he would not comment on “active litigation,” commonwealth law “provides that voters have to both sign and date the declaration envelope.”

Marks added that the department has reached out to the counties and asked them to “segregate those undated ballots and await further instruction from us.”

“Our goal here at the department and the counties is to make sure every vote is counted,” he said. “And we’ll work with the counties whatever the courts decide in that litigation.”

The winner of the Republican Senate primary in Pennsylvania will face Democratic Senate nominee and Pennsylvania Lt. Gov. John Fetterman in November.

The Pennsylvania Department of State also announced on Tuesday that it sent guidance to counties on how to handle ballots with undated and incorrectly dated return envelopes. When counties come across these ballots, they must separate those ballots and make sure they are “maintained, preserved and appropriately logged pending litigation,” the directive said.

While litigation regarding whether counties should count these undated ballots is pending, the Department of State said it is “the Department’s position that ballots with an undated return envelope must also be counted for the May 17, 2022 primary.”

CNN’s Ethan Cohen and Melissa DePalo contributed to this report.