By John Whitesides, Political Correspondent
KINGSTREE, South Carolina (Reuters) - Democrat Barack Obama on Thursday defended the fierce tone of his recent exchanges with presidential rival Hillary Clinton and said he was forced to fight back against her campaign's disregard for the truth.
Obama, an Illinois senator, said he was battling a "tough, well-honed political machine" operated by Clinton and her husband, former President Bill Clinton, but did not think their escalating feud would hurt the party in November's election.
"One principle that I think we want to firmly establish is, if people are making false assertions about my record, we will answer them," Obama, who would be the first black U.S. president, told reporters.
The top two contenders for the Democratic nomination have engaged in a widening war of words, including a debate on Monday in which they traded a series of harsh and sometimes personal attacks.
Obama ran a tough radio ad accusing Clinton, a New York senator who would be the first woman U.S. president, of being willing to "say anything to get elected."
He said it was in response to Clinton's radio ad, which he said distorted his comments about Republican ideas.
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