GMAT Sentence Correction (SC) | Re: In California and New York, Democratic challengers will need

The problem with this question is that for an outsider, this will be a riddle. We do not know the significance of the reference to California and New York in particular. If it were the entire US, then we can understand that the elections were national. Secondly, looking from today’s perspective, this question may not be relevant. May be in 2008, Obama, then a new hand had to beat the more popular Hillary Clinton and prove to the voters that he was better than the Vietnam War hero McCain.