It’s hard to debate that former vice president Joe Biden finds himself in an unusual position in polling for the 2020 Democratic presidential nomination. He has held a broadly unchallenged lead in national polling and continues to be the candidate who polls best against President Trump in prospective 2020 matchups. But he also trails other Democrats in early-state polling, landing in the sort of position in those polls that generally precedes a solemn, regretful announcement from a lectern in February.

Politico’s Natasha Korecki and Marc Caputo offer a number of reasons for that split, including Biden’s pulling back on ads in early states. They also note that Trump’s campaign has been “running anti-Biden ads on TV in Iowa and more broadly over social media platforms like Facebook and YouTube.”

It raises an interesting question. The emergence of the scandal involving Trump and Ukraine has Biden at its center, given the evidence that Trump sought to elicit an investigation of the leading 2020 Democrat from that country’s government. Trump’s ads have focused on the president’s unsupported allegations that Biden acted improperly. Is this having an effect on Biden?

The data don’t really suggest it is. In fact, the details that have emerged over the past month about Trump’s activity don’t even seem to have affected impeachment polling that much, let alone Biden. The most natural explanation for Biden’s two-track polling is the first offered by Korecki and Caputo: He does better with moderate and nonwhite Democratic voters.

Here’s how state and national primary polling has evolved over time, relative to Biden’s position.

Biden’s lead in New Hampshire started to fade in August. His lead in Iowa sank after the debate that month — right before the impeachment inquiry was launched on Sept. 24. His national polling lead started to drop at the same time. His lead in South Carolina, though, has been steady, dipping only in the middle of October.

The lead Biden lost nationally in September wasn’t a function of him, though. It was a function of the rise of Sen. Elizabeth Warren (D-Mass.). In Iowa, it was a combination of Biden falling and Warren rising.

The steadiness of Biden’s support nationally suggests that Trump’s ads targeting Biden nationally didn’t make much of a dent.

One thing that also happened in September was that white voters moved toward Warren. In YouGov-Economist polls conducted in August, Warren earned an average of 23 percent of the white vote. In September it was 28 percent, including 28 percent support in a poll completed on Sept. 3, before the Ukraine questions emerged. In October, Warren averaged 30 percent.

Biden, by contrast, averaged between 18 and 20 percent in all three months. Among black Democratic voters, though, he averaged 40 percent of the vote across those months.

South Carolina is 27 percent black. Iowa is 91 percent white.

It’s still possible that impeachment had some effect, of course. Perhaps white voters were uniquely worried about Biden’s vulnerability to Trump? If so, they weren’t sharing that concern with pollsters. Overall, the percentage of respondents telling YouGov that Biden would probably beat Trump was flat before and after the impeachment inquiry began, suggesting little concern about the issue.

While Biden’s national lead over Warren dipped and recovered, Biden’s polling against Trump remained steady. There was a dip shortly before the inquiry began, in a period when there was a lot of reporting about Trump’s allegations, but Biden’s lead in general-election polling has been relatively steady.

Again, it’s worth noting that on the most direct gauge of how impeachment is affecting the public’s views — that is, on views of the impeachment itself — the past month or so hasn’t shown much change. The percentage of Americans supporting impeachment and removal of Trump in polls aggregated by FiveThirtyEight hasn’t increased much since mid-October.

(Different polls use different questions, which drives some of the scattershot nature of the results.)

This is certainly problematic for congressional Democrats hoping to see bipartisan support for Trump’s ouster. But for Biden, it’s probably somewhat reassuring. If the impeachment inquiry and the evidence that’s emerged isn’t prompting people to rethink their views of what should happen to Trump, it’s hard to believe they’re increasingly concerned about how this secondarily might affect Biden.