Eight Republican candidates are lining up for the first in a series of debates that will help define the party's nomination battle to take on Barack Obama next year for the White House.

The main focus of Wednesday night's debate at the Ronald Reagan Library in the Simi Valley, near Los Angeles, will be on whether Texas governor Rick Perry, who only entered the race last month, can consolidate his frontrunner status.

Tom Mann, a political analyst at the Brookings Institution, said: "It is interesting because of Rick Perry, and the fact that he has sky-rocketed to the lead in the Republican field without many people having a firm hold on him, just some impressions."