Barack Obama has politely but firmly refused to debate Hillary Clinton before the crucial primaries of Indiana and North Carolina that will be held on May 6.

Clinton threw the gauntlet on Saturday challenging the frontrunner to a Lincoln-Douglas style debate with no moderator -- a reference to Stephen Douglas and Abraham Lincoln who ran for the Senate in Illinois in 1858. Abraham Lincoln lost that race but went on to win the presidency.

But Obama said he has other ideas, stressing that he would like to focus by directly appealing to the voters of the two states. "I'm not ducking one. We've had 21... with two weeks, two big states, we want to make sure that we're talking to as many folks as possible on the ground, taking questions from voters," Obama said on Fox News on Sunday. "We're not going to have debates between now and Indiana," he added.

For a person who is trailing in the delegates category as also in the popular vote, the former first lady has been saying that the frontrunner would not debate because he's unhappy with questions from TV moderators during the April 16 debate ahead of the Pennsylvania primary.

After that debate, Obama had complained that it focused too much on political trivia and too little on real issues.

With barely a week to go for the showdown in Indiana and North Carolina, the notion that one or the other candidates is a favourite is far-fetched as polls are consistently showing a tightening of the race, especially in Indiana which at one time showed Obama clearly in the lead.

The Illinois Democrat is currently leading in North Carolina. But with a solid win in Pennsylvania and the fresh injection of funds thereafter, the Clinton campaign decided to launch an aggressive showing in the two states with a conviction that it could carry at least one of them, perhaps Indiana.

If Obama is hoping that Illinois would have a neighbours' effect on Indiana, Clinton hopes that her solid win in Ohio would rub off in Indiana especially in the eastern parts of the Hoosier State.

In Indiana economic issues merit a very high degree of attention,  for the state has lost some 30,000 manufacturing jobs in the past year with some of them as a result of overseas buyouts from countries like China. North Carolina offers 115 national convention delegates, the largest among the remaining nine contests, and Indiana offers 72 delegates.

According to one estimate, in the overall race for the Democratic Party nomination, Obama leads with 1,724.5 delegates, including superdelegates; and Clinton has 1,593.5.

It takes 2,025 to win the democratic presidential nomination.