Republican US Senate candidate David McCormick Monday brought a lawsuit asking a Pennsylvania court to order counties to count undated mail-in ballots from the state’s May 17 primary. The ballots could impact the outcome of McCormick’s primary race against celebrity physician Dr. Mehmet Oz. McCormick is less than 1,000 votes behind Oz.

McCormick, a former hedge fund chief, wants the counties of Pennsylvania to count the mail-in ballots that do not have a date on the envelope but were turned in by the May 17 deadline.

Pennsylvania state law stipulates that a ballot will not be counted if the date is not put on the return envelope.

The lawsuit was filed before the May 26 deadline for Pennsylvania’s secretary of state to evaluate whether a recount is needed. The count from Monday night shows that McCormick has received 45,794 mail-in votes while Oz received 32,944. However, McCormick is slightly behind Oz in the total count.

Ronald L. Hicks Jr., a lawyer for McCormick, wrote in the complaint “These ballots were indisputably submitted on time — they were date-stamped upon receipt — and no fraud or irregularity has been alleged.” Hicks continues to say “The boards’ refusal to count the ballots at issue violates the protections of the right to vote under the federal Civil Rights Act and the Pennsylvania Constitution.”

In a Twitter post Oz’s campaign wrote that McCormick’s lawsuit was “a tactic that could have long-term harmful consequences for elections in the Commonwealth of Pennsylvania.”