Last Updated Aug 14, 2014 4:30 PM EDT
Mississippi state Sen. Chris McDaniel on Thursday filed a formal legal challenge to the June 24 Republican primary runoff that he narrowly lost to incumbent Sen. Thad Cochran, alleging that thousands of votes cast in favor of his opponent were illegal, according to the Jackson Clarion-Ledger.
On Tuesday, McDaniel said his lawyers have a "rock-solid" case to make.
McDaniel's team has argued that thousands of people who voted in the Republican runoff also cast ballots in the Democratic primary earlier in June, which would make their ballots invalid under state law. His team has highlighted affidavits from volunteers flagging thousands of illegal or irregular votes.
Cochran's team has pushed back, saying the race was decided fairly, and with no more irregularities than any other election.
Most legal observers say McDaniel's' case is a long shot. Still, Cochran's margin of victory in the runoff was only 7,667 votes, so the invalidation of several thousand votes, however unlikely, could affect the result.
McDaniel first took his complaints about the runoff election to the Mississippi Republican Party, which promptly volleyed the challenge to the courts, saying it was simply too big an issue for the state party to resolve in a timely manner.
According to the Clarion-Ledger, Mississippi Supreme Court Justice William L. Waller Jr. will appoint a special judge to preside over the case. There is no deadline for the court to reach a decision, but ballots for November's general election bearing either Cochran's or McDaniel's name must be delivered to county clerks by September 10.
Whatever the final outcome, McDaniel's challenge endured an embarrassing hiccup this week, when observers spotted a curious pair of names on a list of hundreds of allegedly invalid votes circulated by McDaniel's attorney Mitchell H. Tyner on Monday.
Among the hundreds of allegedly fraudulent voters listed on an affidavit bearing Tyner's firm's letterhead were Tyner himself and his wife Sloane. Both were described as having "voted written in margin and on June 24," implying that they voted in the June 3 Democratic primary before crossing over to vote for Cochran in the June 24 GOP runoff.
Cochran's adviser Austin Barbour said Tuesday that the Tyners' appearance on the affidavit provides "another example" of how "absurd" McDaniel's case is, according to the Clarion-Ledger.
McDaniel's challenge represents the last hope for grassroots tea party groups hoping to claim an incumbent senator's scalp in 2014. After watching several former colleagues felled by primary challengers in 2010 and 2012, incumbent Republicans steeled themselves for another difficult primary season at the start of the cycle. As the year wore on, though, challengers initially seen as formidable began to lose steam, from Kansas to Kentucky. If Cochran prevails, the 2014 election cycle will be the first time since 2008 that every Senate Republican seeking reelection has been re-nominated.