Barack Obama likened Hillary Rodham Clinton to President George W. Bush on Sunday as they clashed over foreign policy with two days to go before the Indiana and North Carolina primaries that are crucial to the presidential fortunes of both Democratic contenders.

Obama scolded Clinton for saying that the US would “totally obliterate” Iran if it attacks Israel. Clinton stood by her comment.

The foreign policy dustup came as the two candidates appeared separately on duelling Sunday news shows and as the drawn-out fight for the Democratic nomination grew ever more fierce ahead of Tuesday’s pivotal pair of primaries.

Both candidates were focusing the bulk of their Sunday campaigning on Indiana, where polls show the race extremely close. They stayed overnight in Indianapolis hotels one block apart, and both were campaigning within miles of each other in Fort Wayne before returning to the capital city for the Indiana Democratic Party’s Jefferson Jackson Dinner.

But North Carolina was getting some last-minute attention, too. Both candidates shuffled their schedules to dart back to the state on Monday, reflecting the tightening contest there; polls show Clinton trimming Obama’s lead.

Clinton suggested anew she had no intention of dropping out, saying on ABC television’s This Week: “When the process finishes in early June, people can look at all the various factors and decide who would be the strongest candidate” to go up against presumptive Republican nominee John McCain in the fall.

But an Obama victory in both Indiana and North Carolina could lead to a rush among remaining uncommitted superdelegates to declare their support for the Illinois senator and give him enough delegates to claim the nomination. A split decision or a Clinton victory in both states could raise doubts among superdelegates about Obama’s electability and prolong the contest past the last two primaries in Montana and South Dakota on June 3.