The White House is in current discussions on sending a senior admin official to Kiev, following UK Prime Minister Boris Johnson's surprise trip last week. Also this week Polish President Andrzej Duda and the presidents of Lithuania, Latvia and Estonia did the same, where they met with Volodymyr Zelensky. It appears the White House needs a 'symbolic' show of solidarity in Ukraine's capital too.
Biden has been under pressure to "do more" regarding Ukraine, after this week signing off on $800 million more in military aid to the country, and on Wednesday The New York Times reported that it remains highly unlikely that either Biden or Vice President Kamala Harris would be the ones to go.
Biden's advisors perhaps have his Warsaw trip in mind, which left them in a scramble to walk back certain statements that unnecessarily provoked Russia (such as telling 82nd Airborne troops they were about to enter the Ukraine conflict). There's also the obvious security nightmare entailed in a scenario of a sitting US president entering a war zone.
Admin sources told Politico, meanwhile, that the likely choice for a high level trip to Ukraine's capital would be Secretary of State Antony Blinken or Secretary of Defense Lloyd Austin, but that sending Biden or Harris is still a possibility, albeit remote.
"No decision on the potential visit has yet been made as deliberations continue inside the White House. President Joe Biden and Vice President Kamala Harris remain candidates to represent the U.S. in the Ukrainian capital, though it’s far more likely that a Cabinet member like Secretary of State Antony Blinken or Defense Secretary Lloyd Austin will go, the officials said," Politico wrote.
Reports say discussions are still ongoing, and that the world would likely learn about such a trip the moment the official shows up, given the constraints of safety and security.
Such a visit would merely be on the symbolic level, in order to show "solidarity" - and so may not be considered worth it from Washington's vantage point. It could also be seen as an escalation by Moscow, given any top US official would have to be accompanied by military personnel and a huge security presence.