蜜芽传媒

Donald Trump continued to dominate the Republican race for US president by causing further controversies in the first debate.

The tycoon's refusal to rule out a third-party run damaged his chances, said former Republican strategist Ron Christie.

"Americans are extraordinary loyal to their party of preference."

Mr Trump "really lost an opportunity from a perspective of gaining credibility" to people who consider him as a reality talk show host, said Mr Christie.