Barack Obama is talking about the elephant in the race today: Republican John McCain. And he's been largely ignoring his rival for the Democratic nomination, Hillary Rodham Clinton.
Both Democratic contenders have been campaigning in Pennsylvania today, where recent polls give Clinton a double-digit lead. But Obama spent much of the day focusing on his differences with McCain.
The Illinois senator says while McCain's biography is "worthy" of admiration, he has arguments with the likely Republican nominee's policies. Obama cast a McCain presidency as a four-year extension of President Bush's economic and military policies.
Obama also responded to McCain's criticisms that he's inexperienced on national security matters. Obama says McCain would keep thousands of troops in Iraq for as long as 100 years and that would be "wrong" for both national security and the economy.