Ten Republican contenders for the 2008 US presidential election are preparing to take part in their first debate.
Among those to brave the TV cameras at the Ronald Reagan Presidential Library in Simi Valley, California, are Rudi Giuliani, John McCain and Mitt Romney.
Lesser-known candidates are hoping to raise their profile ahead of the primary elections early next year.
The event comes a week after eight Democratic presidential hopefuls held their first debate in South Carolina.
The Republican debate will be broadcast on cable channel MSNBC from 2000-2130 EST (0100-0230 BST).
It is being co-hosted by Washington-based blog site politico.com, which has invited questions to be put to the candidates.
Iraq support
The debate will be the first opportunity for many potential voters to compare all the declared Republican candidates as they give their views.
Former New York Mayor Rudi Giuliani is currently leading the polls, having taken a lead over rival Senator John McCain, whose campaign has failed to catch fire in its early stages.
Former Massachusetts Governor Mitt Romney, who did well in fundraising for the first quarter of 2007, will hope to extend his appeal and improve his public opinion poll ratings.
The issue of the Iraq war is expected to dominate, with the contenders - notably Senator McCain - likely to be questioned over their support for President George W Bush's strategy in Iraq.
Other issues on the agenda are likely to include health care, the US fight against terrorism and the environment.
Candidates can each expect to have between seven and 10 minutes air time in the course of the 90-minute debate.
California clout
The debate's location in California takes on extra significance given its recent move to bring forward the date of its primary by four months, to 5 February 2008.
In previous years, nominations have essentially been decided by the time California - the most populous state in the US - chooses its delegates to the parties' national nominating conventions.
This time round, California will have more clout, meaning Republican and Democratic contenders will be keen to make an impression there.
Presidential candidates have usually campaigned little in California, but used the wealthy state as a source of funds for primary contests elsewhere.
Nancy Reagan, President Reagan's widow, is expected to attend the debate at her late husband's namesake library but is not scheduled to speak.
Announcing the event earlier this year, she said: "Ronnie always hoped the library would be a place where policymakers will debate the future.
"This presidential debate provides the opportunity to fulfil his wishes."
REPUBLICAN CANDIDATES
Sam Brownback
Jim Gilmore
Rudy Giuliani
Mike Huckabee
Duncan Hunter
John McCain
Mitt Romney
Ron Paul
Tom Tancredo
Tommy Thompson