How so? According to what statute? Or, what legal process?
In practice, the only active authorities have been the respective Secretaries of State of a handful of states, acting independently. Even after receiving notification in advance and being sued, most did not act to try to verify Obama (or Kamala, for that matter).
According to THIS particular text found in the Twentieth Amendment.. ”or if the President elect SHLL HAVE FAILED to qualify”.
This is describing an action, “qualifying” that someone FAILED to do. That someone is clearly stated to be “the President Elect”. In this case, Obama. The burden of proving his eligibility was his responsibility. The burden of Congress was to verify and approve his submission or to name an interim President who WAS eligible to serve. This did not happen and a usurpation of the office of President occurred.