So it's ok as long as the other one did it first?
Well I guess that is maybe how you view it as I never said that, nor anything close
No comparison IMO. McCain stated he will hate a ethnic group till he dies, words from his very mouth which despite requests he refused to apologise for years. Obama himself did not do this, some volunteers did, which apart from the fact that media reported it that way, common sense says the candidate himself is not out at the front of rallies acting as an usher.
Nevertheless, within 24 hours after this, Obama issued an apology for the volunteers actions by calling both women personally.
Quote from one lady: "Senator Obama has called us each to personally convey his deepest apologies and acknowledge that this was inexcusable. We both immensely appreciate the Senator’s phone call and his commitment to remedy this issue. We commend him for displaying qualities befitting an effective President".
Link