If Mayor Vincent C. Gray continues to refuse to explain to District voters what went wrong in his 2010 campaign, then he needs to resign.

Otherwise, he has no right to be mayor, now that it was confirmed in federal court pleadings last week that his campaign cheated by making secret payoffs to fringe mayoral candidate Sulaimon Brown.

I’m open to the possibility, albeit skeptical, that Gray (D) could provide a reasonable, defensible account of why he should continue to draw his $200,000 salary. Based on what we know so far, the campaign sleaziness wasn’t big enough to have played a decisive role in procuring his landslide victory over incumbent Adrian Fenty (D).

I interviewed six top officials from both sides of the campaign — three from Gray’s camp and three from Fenty’s. None of them thought that Brown’s role in the election, by itself, significantly affected the result of the September 2010 Democratic primary.

Bill Lightfoot, who was co-chairman of the Fenty campaign, said, “We knew already in May and early June, before they did anything illegal, that Adrian was in very deep trouble, because people just didn’t like him.”

Indeed, the great tragedy and irony of this whole affair might be that dirty tricks needlessly sabotaged Gray’s reputation and crippled his administration, because he would have won without them.

But there are three important reasons why the mayor, if he wants to stay in office, has to give voters a thorough, transparent account of who messed up and how in the political operation that put him there.

First, the election result might have been different had voters known that parts of Gray’s campaign were crooked. It’s strange to remember today, but one of Gray’s main selling points was the perception that the Fenty administration was rife with cronyism.

Now we know the integrity pitch was a sham. Two Gray campaign staffers, Thomas Gore and Howard Brooks, said in guilty pleas that they helped slip money secretly to Brown to encourage him to continue to make a hyper-aggressive verbal assault on Fenty in campaign forums. They subsequently broke the law in trying to cover up their illicit activity.

“Gray was viewed as a reformer, as somebody who would come in and change the system. If something like this had leaked out two or three weeks before the vote, it would have had an impact and would have put Gray in the same category as Fenty,” said a Gray campaign adviser, who spoke on the condition of anonymity to avoid alienating colleagues from the campaign.

Second, the campaign’s wrongdoing might prove to be much more extensive than the payoffs to Brown. The U.S. attorney is also investigating whether Gray benefited from a “shadow campaign,” in which off-the-books campaign contributions helped pay for get-out-the-vote efforts on Election Day.

The officials from Gray’s campaign said flatly that any shadow campaign was nowhere near large enough to affect the final result. The ones from Fenty’s side tended to agree but didn’t rule out that it could have made the difference.

“If it was a big number [of dollars], the answer is, yeah, it could have” changed the outcome, said Fenty strategist Tom Lindenfeld. “No matter what the number is, to run a campaign in which a significant aspect is breaking the law sets a standard that undermines our government beyond what we can tolerate.”

Finally, Gray has to come clean about his own mistakes and culpability. At the least, he made some really lousy hires and provided severely inadequate oversight. At worst, he broke campaign laws and has been brazenly lying to the public for 14 months.

Gray’s continued silence on this has become untenable. He has said from the start that he never knew anything about any payments to Brown and that he couldn’t imagine that anybody on his staff would do anything so “reprehensible.”

Now two of his staffers have confessed to doing just that. So, Mr. Mayor, even if we believe that you didn’t know anything yourself, where are the public denunciations of those who betrayed you? Where’s the apology to the public for hiring these people and failing to supervise them? Where’s the mea culpa for running a dirty campaign?

But Gray is saying nothing. He’s gone mum on the strict orders of his high-powered attorney, Robert S. Bennett.

One reason, supposedly, is that any comment from Gray might help others under investigation make up stories to benefit themselves at his expense.

That might be a good legal strategy, but it’s no basis for governing a city. It’s time to clear the air and accept the consequences or step down.

For previous columns by Robert McCartney, go to washingtonpost.com/mccartney.