Regardless of where one stands on impeachment, two facts are indisputable: President Trump asked Ukraine to investigate Joe and Hunter Biden, and his administration delayed Congressionally-appropriated aid to the country. It’s the potential link between these actions that has emerged as a central question.

Sure, there are those who would argue that Trump’s request to Ukrainian President Volodymyr Zelensky that the country look into the Bidens itself is impeachable. And there are those who may take a “so what?” attitude even if aid were used as leverage. But undoubtedly, if it were established that Trump withheld aid as leverage to coerce a foreign government to investigate a political rival, it would move more people into the impeachment column, and would make the politics of defending Trump much more difficult for Republicans to navigate.