U.S. Democratic presidential candidate Barack Obama says he does not believe race is a central issue in November's election that could make the Illinois senator the nation's first black president.

Senator Obama said in a television interview with Fox News Sunday that while race is still a factor in American society, he believes voters care more about electing a president who can solve their problems. Obama also said he needs to do more to raise his profile among working-class voters by "knocking on more doors," so that people become more familiar with his views and values.

Obama lost last Tuesday's presidential primary in Pennsylvania to fellow Democrat Hillary Clinton. The New York senator has challenged him to participate in a debate without moderators before the next primaries, which are scheduled for May 6 in the states of Indiana and North Carolina. Obama has turned her down.

However, Obama says he would be "more than happy to consider" another debate after those two contests are over.

Separately, the presumptive Republican presidential nominee, Arizona Senator John McCain, spent Sunday campaigning in the southeastern state of Florida. At a campaign event, McCain was asked about a report in The New York Times newspaper that said over a seven-month period beginning last year, he used a corporate jet almost exclusively for campaign-related purposes.

The Times said the jet was owned by a company headed by his wife, Cindy McCain, and that it was used at little cost. Senator McCain told the reporter that use of the aircraft was "perfectly legal and appropriate."