A US man stabbed his relative after an argument over the presidential credentials of Barack Obama and Hillary Clinton.

Brothers-in-law Jose Ortiz and Sean Shurelds were arguing about the fiery contest for the Democratic nomination for president at their Pennsylvania home when the dispute escalated into violence, US broadcaster CBS said.

US authorities said Ortiz, a registered Republican and Clinton supporter, allegedly stabbed Mr Shurelds, an Obama supporter, in the stomach, CBS said.

Source: theage.com.au