Tea Party candidate Chris McDaniel delivers a concession speech in Hattiesburg, Mississippi. (Jonathan Bachman/Reuters)

IT TOOK just a few words for state Sen. Chris McDaniel to stoke tea party fervor after his runoff loss in the Mississippi Republican primary to incumbent Sen. Thad Cochran. “We’re not done fighting,” he said defiantly to the June 24 election-night crowd.

A messy primary was about to get worse. Mr. McDaniel, who lost by about 7,600 votes, claimed that there were voting “irregularities,” insisting that those who voted in the June 3 Democratic primary illegally cast ballots three weeks later in the Republican runoff. He also argued that many voters broke an obscure and unenforceable Mississippi law that prohibits citizens from participating in a primary unless they intend to back the party’s nominee in the general election. Because Mississippi does not register voters by party, Mr. Cochran had focused on getting more left-leaning, African American voters to the polls for the runoff.

One month later, the McDaniel campaign is embroiled in a court fight over unredacted access to original voting records. This month, it offered 15 bounties of $1,000 each for any evidence of voter fraud. Campaign officials say they have found 8,300 questionable ballots from the records that they’ve examined, and Mr. McDaniel’s attorneys indicated last week that a challenge of the result would be filed by this coming weekend.

But Mr. McDaniel still has offered no evidence to back up his claims. His spokesman, Noel Fritsch, told us that the delay was “to make certain that we have our ducks all in a row.” Mr. McDaniel has now embarked on what he calls a Truth and Justice bus tour to rally supporters around the state. His campaign Web site states plainly: “Democrats steal the Mississippi runoff.”

The close election displays in full light the ongoing push-and-pull between the tea party and establishment Republicans. It also reveals the tea party’s troubling alienation of minorities — a key reason Republicans can win district seats but have difficulty in national elections.

But Mr. McDaniel’s challenge of the election’s legitimacy isn’t just a party problem. In even the closest primaries, such as Tuesday’s narrow GOP election in Georgia, the loser typically concedes in a bid for unity. Since elections inevitably have a few voter irregularities caused by human mistakes, the burden of proof to challenge an election is high — as it should be.

Mr. McDaniel’s strong language and incendiary tactics have no place in our democratic process. Any challenge to an election must be open and respectful. If Mr. McDaniel would like to contest the results, he should end his campaign spree and present evidence of widespread fraud. If not, he must do what he should’ve done a month ago: concede.