New York( CNN) When President Donald Trump and his Ukrainian counterpart Volodymyr Zelensky meet formally for the first time on Wednesday, what was once viewed as a routine diplomatic sit-down will now be one of the most closely scrutinized encounters of Trump's presidency, thanks to the swirling impeachment crisis.

The 2:15 p.m. ET meeting was arranged well before the whistleblower disagreement exploded into public view, according to people familiar with the plans. Aides initially did not view it as a major highlighting of Trump's agenda at this week's United Nations meetings, which they expected would focus heavily on Iran and not on the questions of abuse of power.

Now, officials say they view the session as an important venue for Trump to counter Democratic accusations of wrongdoing.