Rather than rejecting Hamas' existence, Obama is treating Hamas like a legitimate government that he expects Israel to negotiate with.
Before Obama's trip to Israel, he met with two organizations that support Hamas. And one of those organizations provided him with pro-Hamas proposals.
During his trip, his language suggested that his administration was softening its line on Hamas, calling on it not to engage in violence, rather than condemning it.
Elder points out the difference between the way that Obama talked about Hamas and Hezbollah. When referring to Hamas, Obama said;
"That’s why we have made it clear, time and again, that Israel cannot accept rocket attacks from Gaza, and have stood up for Israel’s right to defend itself. And that’s why Israel has a right to expect Hamas to renounce violence and recognize Israel’s right to exist."
Obama Inc. actually pressured Israel into calling off a ground assault, but let's skip over the fact check. While Obama does say that Israel has the right to defend itself, he does not condemn Hamas.
Instead he makes a 'peace process' like statement that Israel has the right to expect Hamas to renounce violence. (This is not quite the same thing as Obama saying that he demands that Hamas do this.) The statement is meaningless except as a prelude to negotiations. Rather than rejecting Hamas' existence, Obama is proposing terms on which Israel should negotiate with Hamas.
On the other hand when it comes to Hezbollah, Obama offered a strong condemnation;
I think about five Israelis who boarded a bus in Bulgaria, who were blown up because of where they came from; who were robbed of the ability to live, and love, and raise families. That’s why every country that values justice should call Hezbollah what it truly is – a terrorist organization. Because the world cannot tolerate an organization that murders innocent civilians, stockpiles rockets to shoot at cities, and supports the massacre of men, women and children in Syria.
Apparently the world can tolerate Hamas... but not Hezbollah.
What's the difference? Focus on the last 10 words. Hamas is part of the Sunni coalition and linked to the Muslim Brotherhood. It's on the "right side" of the Syrian Civil War. Hezbollah is part of the Shiite coalition. It's on the "wrong side" of the Syrian Civil War.
And this isn't a one off. Here is how Obama discussed Hamas in his Ramallah press conference with Abbas.
I would point out that all this stands in stark contrast to the misery and repression that so many Palestinians continue to confront in Gaza — because Hamas refuses to renounce violence; because Hamas cares more about enforcing its own rigid dogmas than allowing Palestinians to live freely; and because too often it focuses on tearing Israel down rather than building Palestine up. We saw the continuing threat from Gaza again overnight, with the rockets that targeted Sderot. We condemn this violation of the important cease-fire that protects both Israelis and Palestinians — a violation that Hamas has a responsibility to prevent.
This is being described as a condemnation, but really it's Obama treating Hamas like a legitimate government that he expects to behave according to American standards.
It's long way from treating Hamas like a terrorist group. This actually represents the growing legitimization of Hamas.