Trump accuses Biden of taking Hamas's side, reiterates that war wouldn't have happened if he were president.
US support is vital; it would be best if Israel does not ignore its concerns, says writer.
The delay is an alleged attempt by the US to send a message to Israel about operating in Rafah without an appropriate and credible humanitarian plan.
Biden urged Sisi and Qatar's Emir Sheikh Tamim bin Hamad Al Thani, whom he spoke to separately, to exert all efforts to secure the release of hostages held by Hamas.