I'll start by saying that I think the time has come for the US to come out and openly call for regime change - including the departure of Mubarak in very short order - or at least publicly endorse any evidence that Egypt is on that path. That said, I'd like to defend the Obama administration's response to the crisis in Egypt so far.
There is increasing talk about resentment being directed at the United States because the Obama administration has not been seen to do more to get rid of Mubarak. The assumption seems to be that the Obama administration is torn between their loyalty to Mubarak and their pro-democracy principles. Along with this seems to be that the US is either continuing to prop up Mubarak or at best doing nothing to get rid of a dictator who is their responsibility. But I think these critiques are not 100% valid.
First, Mubarak was not put in power by the US. Unlike many tin pot dictators around the world in the past 50 years or so (Pinochet, Marcos, Samoza, Batista etc), it's very hard to make the case that the current regime in Egypt was installed by the US. Mubarak's regime can trace its lineage with unbroken line of succession to the military regime of General Gamal Abdel Nasser. Nasser was a Soviet protege, not a US one. Nasser was succeeded by his long time friend and political ally, General Anwar El Sadat. Sadat was initially a Soviet client as well. It was only after the Egyptian military recognized the unfeasibility of a military solution the existence of Israel and he decided to shift away from a war policy to a peace policy, that Sadat also moved away from the USSR and towards the USA. When Sadat was assassinated for that shift, he was succeeded his protege, General Hosni Mubarak. Mubarak also began as a Soviet client - he graduated from a post-graduate training program at the USSR's Frunze Military Academy. My point here is that this is not a case of the US installing a despicable regime for its own purposes. Rather Egypt's military regime came to the US and offered its services and the US accepted - gladly.
Second, from very early on in this crisis, statements by both President Obama and Secretary of State Clinton have pointedly avoided mentioning Mubarak by name even while singing the praises of the friendly relations between Egypt and the United States or the "Egyptian people" and the United States. In a crisis like this for the US to make a point of not mentioning Mubarak by name is tantamount to a withdrawal of support. When these ominous omissions are combined with direct admonishments against using violence to put down the uprising, these kinds of statements amount to announcing US preference for Mubarak to leave (on the assumption that Mubarak can't stay without a crack down and the demonstrations won't stop until Mubarak goes). These basic statements have been embellished with progressively more direct calls for "dialogue," "reform," "transition," and "democracy." I'm increasingly convinced that all the evidence points to the US government effectively throwing Mubarak under the bus.
Third, suppose President Obama had come on TV on Wednesday of last week and said something like "the United States is calling for the resignation of President Mubarak..." That would probably cause celebrations in the streets in the short term. But it would have risked making whatever transitional government replaces Mubarak look like exactly the kind of US installed puppet, that Mubarak never really was. Some might also argue that such a move would have alienated some other US allies in the region with authoritarian regimes. But other than Yemen - which is teetering regardless of what Obama says about Mubarak - I'm not sure which other crucial allies would be likely to reverse their pro-US stance over this. I think the main motive for Obama's caution is a fear that the new regime in Egypt would appear to be anything other than a government of, by and for Egyptians.
This is certainly a messy situation and I'm not trying to say reasonable people wouldn't disagree about what exactly Obama should say and when. But I do think there is an increasing trend in the press - picking up on anger being voiced in Egypt and around the world - that Obama is either somehow pro-Mubarak or feckless.