That has provided Mr. Obama with the opportunity, which he plans to seize in a more full-throated way starting on Wednesday, to argue that voters across a wide cross-section of the country have embraced his candidacy, and that the time has come for the group that could hold the balance of power, those 796 unpledged superdelegates — party leaders and elected officials who have an automatic seat at the national convention — to follow suit.
Source: wiktionary