When is the third Republican US presidential debate and who are the candidates?

Republican presidential contenders are scheduled to face off in a third primary debate on Nov 8. Here are some facts about the showdown:

Where is it?

The third debate will take place in Miami, though the Republican National Committee has yet to specify the venue or exact time. Florida is the home of former president Donald Trump and Florida Governor Ron DeSantis, who are running first and second in national opinion polls, respectively.

Florida was until recently a battleground between Republicans and Democrats, but the state now leans conservative. The state hosts a Republican primary contest in March, which has played a crucial role in previous primary elections, though it is considerably less important than contests in Iowa, New Hampshire and South Carolina, which are slated for January and February.

Who is eligible?

To qualify for the debate, a candidate will need to receive at least 4% in two national polls or 4% in one national poll as well as 4% in a poll in at least two "early states." Those early states are Iowa, New Hampshire, Nevada and South Carolina, all of which are among the first to hold nominating contests. The Republican National Committee has laid out several requirements for surveys to count toward this requirement, including that they must take place after Sept 1.

Candidates will also be required to have at least 70,000 unique donors, including at least 200 donors from 20 or more states or territories. They also must sign a pledge which requires participants to support the eventual Republican nominee.

Will Trump be there?

Trump holds a 37-percentage point lead over DeSantis, his closest challenger, according to the latest Reuters/Ipsos poll, limiting the debate's significance if he is not there.

Trump opted out of the first two Republican debates, saying it would be "stupid" to expose himself to attacks from opponents after he previously implied he would not participate in any of the debates. While the possibility that Trump changes his mind cannot be ruled out, his campaign advisers on Oct 2 called for the RNC to cancel the upcoming Miami debate.

Which other candidates will be there?

DeSantis, former US Ambassador to the United Nations Nikki Haley and tech entrepreneur Vivek Ramaswamy appear to have the support needed to make the debate stage. Former Vice President Mike Pence, former New Jersey Governor Chris Christie and South Carolina Senator Tim Scott also appear to have a solid shot of being there, according to recent polls.

North Dakota Governor Doug Burgum faces longer odds. Former Arkansas Governor Asa Hutchinson, who did not qualify for the second debate in California, is unlikely to be there, unless his fortunes change.

How much will the debate matter?

The November debate could make a difference for some candidates, but is unlikely to change the fundamental dynamics of the race. After the first presidential debate in Wisconsin, for instance, Haley received a measurable polling boost and renewed interest from donors thanks to a well-received performance. Still, that debate did not dent Trump's massive lead.

With the third debate just over two months before the first primary contest in Iowa in January, the candidates will be under intense pressure to begin chipping away at Trump's lead.