I noticed this little detail in the NYT article: "... Ukraine until officials there helped with investigations into Democrats including the Bidens, according to unpublished ..."

This implies there were other democrats. So unless all democrats are considered direct rivals, i.e. presidential rivals, this reinforces Trump's defense claim that he was just looking into general corruption, not just at his potential rival Biden.

Assuming of course any of these claims are true, which is not established at all.