PHILADELPHIA — The Republican National Committee says it will intervene to oppose David McCormick’s lawsuit to count undated mail ballots in the ongoing vote count for the GOP Senate primary. RNC chair Ronna McDaniel said in a tweet that the national committee, along with the state GOP party, would motion to intervene in the lawsuit filed Monday. In doing so both the RNC and the state party take the position of Mehmet Oz’s campaign. “Pennsylvania law is clear: undated absentee ballots may not be counted,” McDaniel said. “Changing the rules while votes are being counted undermines the integrity…