When I asked D.C. Mayor Vincent C. Gray (D) this week why he is running for a second term, he replied simply but with firmness: “I’m doing what I want to do.”

I have known Gray for nearly 50 years. I met him the week I came to the District in August 1964. It was fraternity rush week at George Washington University, and, as a freshman, I visited all the frat houses. At Tau Epsilon Phi, I was introduced to the president. Here was this tall African American leading a Jewish fraternity. That was highly unusual at that time.

I remember thinking that this was an individual who must possess a tremendous amount of self-confidence. There were few blacks on the GW campus then, and Gray was not just holding his own but also serving in an elected leadership position. This is crucial to understanding who Gray is. He’s a guy who knows how to defy the odds and come out on top.

Gray was also an outstanding athlete. He was scouted by Major League Baseball teams and was an all-star intramural basketball star when I was at GW. In fact, he was good enough to play on the varsity basketball squad, but there was an unspoken policy at GW in 1964 to allow blacks to play football but not basketball. Even though he was a gifted athlete, he was excluded from participating.

My sense has been that this had a profound effect on him. He seems to have decided early on that he would not accept or accommodate himself to conventional behavior or norms.

In the years since, this formula has worked. He entered political life by winning a D.C. Council seat from a three-term incumbent (Kevin Chavous in Ward 7). Then, just two years later, voters citywide elected him chairman of that body. Two years after that, he took on and beat incumbent Mayor Adrian Fenty (D) by 10 points. It’s often forgotten just how much of a feat that was; in the Democratic primary four years earlier, Fenty won every precinct in the city.

My point is, Vince Gray should not be underestimated — but neither should the challenge before him.

For the entirety of Gray’s term, a federal criminal investigation has been hanging over his head. Four campaign aides have pleaded guilty to felonies in connection with the 2010 race. Two of them were particularly close advisers, Jeanne Clarke Harris and Vernon E. Hawkins, and they are now cooperating with federal authorities as they await sentencing. Harris has admitted in open court that at least $650,000 in unreported funds was spent on a “shadow campaign” conducted on Gray’s behalf.

In response to all of this, the mayor continues to say, “I didn’t do anything.” To many voters, this is a highly inadequate answer. Many will not consider voting for Gray unless U.S. Attorney Ronald C. Machen Jr. declares publicly that the mayor will not be charged with any crime.

But how many? To understand the 2014 campaign, one element is essential. To win the Democratic primary on April 1, which in the District is tantamount to winning the general election, you don’t need to get above 50 percent of the vote. You need a simple plurality.

There is no runoff in the District, and all one needs to claim victory is to get one more vote than the second-place finisher. In a multi-candidate race that includes four D.C. Council members plus other serious challengers, the winner might finish with less than 30 percent of the vote. Who’s more likely to get that than Gray?

Right now, even with all his problems, Gray is the front-runner. And if I can see that, so can he. Once again, he won’t let himself be stopped from determining his own fate.

The writer is a D.C. political analyst and a contributor to BBC on American politics.