Consider the part in bold:
Show the elected official why they’re correct on an issue—they don’t necessarily know why they’re correct on an issue—and lay out a path to victory on the legislative front.
You might argue that this is bad because it looks like the sentence might terminate after the word "issue" as follows:
Show the elected official why they’re correct on an issue—they don’t necessarily know why they’re correct on an issue.
But then when you get to the word "issue" your eyes see "Oh, another dash...and now more text". So your eyes see "—and..." and see the remaining part of the sentence that continues right up to "front.". So maybe that's bad because it's like "Surprise! The sentence keeps going!".
And here's a similarly concerning sentence:
As for policy, most Americans tend to agree with Democrats—especially on economic issues—as long as the polling questions avoid loaded terms like “liberal” and “conservative”.
And the bold is potentially another case of potential ambiguity:
Younger Democrats have to start building better connections—either through the grassroots or through big donors—so that they can build name recognition.