We flagged a new Quinnipiac University survey over on Post Politics earlier that shows New York City Public Advocate Bill de Blasio not only leading the Democratic mayoral field by a wide margin, but on the verge of avoiding a runoff.

It's a pretty remarkable rise for a candidate that once looked to have little chance of winning.

Not too long ago, de Blasio was firmly in fourth place and Anthony Weiner was winning. But in the last two and a half months, the two campaigns have been going in opposite directions, as the chart below shows. As de Blasio has excelled, the news that Weiner continued participating in sexually explicit online interactions even after resigning from Congress has sunk his chances.

So is Weiner's fall responsible for de Blasio's rise? Not necessarily.

"I don't think that it's because of Weiner," said Quinnipiac pollster Maurice Carroll. "If you look for an explanation of why de Blasio is up, I'll give you one word: liberal."

Indeed, de Blasio, campaigning as the most liberal candidate in the field, is performing well among left-leaning likely primary voters. He's winning half of those who describe themselves as "very liberal" and 42 percent of the "somewhat liberal" likely voters, according to the latest poll.

De Blasio is also doing well with black voters, among whom Weiner was once strong. De Blasio's wife, who is black, has been a prominent figure in the campaign. And the public advocate's first TV ad featured his son.

De Blasio is pulling about one in three black voters. Former city comptroller Bill Thompson, who is black, gets one in four black voters, a drop from two weeks ago when Thompson was leading de Blasio by 17 percentage points among blacks.

Two other notable points: 1) De Blasio is also doing well among men. 2) The attention the city's controversial "stop and frisk" law has received, following a judge's recent ruling that the law is unconstitutional, also appears to be helping him. Among those who opposed the law in the poll from two weeks ago, de Blasio led with 34 percent.

It remains to be seen whether de Blasio's unlikely rise will propel him to the nomination or not. The next 13 days will determine that. But it's worth bearing in mind that while the fall of Weiner has been one of the defining story lines of the race, the rise of de Blasio, even if not directly connected, is perhaps even more remarkable.