Six factors that will shape the final presidential debate

1. Donald Trump will bring President Obama’s half-brother Malik as a guest
The Republican nominee needs a bombshell to turn things around.

This is light artillery.

The ne'er-do-well Malik Obama comes from a long tradition of presidential siblings who get in minor trouble non-stop (older readers will remember Roger Clinton and Billy Carter).

Malik is by all accounts an ardent Trump supporter. But really, so what? He’s little known, has no killer goss about his brother and, regardless, it’s not Barak who’s running for election.

Mr Trump has also invited Patricia Smith, the mother of IT contractor Sean Smith, who died in the 2012 attack in Benghazi, Libya on a US compound. That’s steelier but the nominee and Republicans in general have long tried to taint Hillary Clinton over her involvement in the incident (or non-involvement) when secretary of state without any success.

2. Millions of Americans have already voted
Just over two million Americans have cast an early vote so far and the number is ticking up fast.

One in three are expected to cast an early vote ahead of election day on November 8.

If Mr Trump (or Wikileaks) has any bombshells left to lob, now is the time.

3. Chris Christie went out for a burger and never came back
Chris Christie has been one of Mr Trump’s strongest “super surrogates.”

But over the past day or two, US media has cottoned on to the fact that the New Jersey governor has quietly removed himself from the campaign trail since the “Access Hollywood” tape.

That's a major blow to Mr Trump. The big man could have been a big help in battleground states over the final three weeks.

Another Trump confidant, former Fox News boss Roger Ailes, seems to have also decamped.

4. Donald Trump’s position in the polls is near terminal
He trails Hillary Clinton by an average six points in one poll-of-polls. That doesn’t sound so bad but the presidential election is decided on (mostly) winner-takes-all voting for each state, and the Republican nominee is behind in all of the 10 major battlegrounds bar the toss-up Ohio. In most cases, he’s losing ground.

Mr Trump also risks losing Texas, where one poll has him just four points ahead of Mrs Clinton and another just three points ahead. In modern times, Republicans have carried the state by huge margins. In 2004, George W Bush carried Texas 61% to 38% against John Kerry.

Another poll has Mr Trump and Mrs Clinton in a statistical dead-heat in Utah (where registered Republicans outnumber Democrats by 4 to 1) – thanks to locally-based presidential candidate Evan McMullin, a Christian conservative, who says he’s disgusted by Mr Trump’s behaviour.

5. The Republican Party is now at serious risk of losing the Senate
Mr Trump needs to drop a bombshell, or perhaps a nuke, in today’s debate to have any hope of turning the race around.

Conversely, Mrs Clinton will be looking to keep things on the level, and simply not make any major mistakes.

But whatever the Republican’s game plan, he may well be provoked to go on the front-foot when Mrs Clinton raises the new groping allegations, and his feuding with Republican Party leaders – who have dismissed his claims the election will be somehow rigged (notably, the Wall Street Journal, which is usually, of course, the Republican nominee at this point in a race, is having a laugh over the rigging claim). 

But the danger for Republicans standing for re-election for Congress is that while Mr Trump going feral on Mrs Clinton might suppress turnout among Democrats, they could also become collateral damage.

While the Republicans' huge majority in the House of Representatives will probably be safe (if diminished), the party’s majority in the Senate is under serious threat. Assuming Mrs Clinton wins the White House, the Democrats need a net gain of four to take control of the 100-member upper house.

A New Yorker state-by-state analysis indicates Republicans are set to lose the Senate. In short, the party’s candidates are in a terrible bind, post-“Access Hollywood” tape. Poll after poll shows a majority of Americans overall strongly disapprove but Mr Trump’s base are standing by their man, and some are refusing to support any local Republican candidate who doesn’t. Thus we get excruciatingly-worded statements from GOP candidates on how they find Mr Trump’s words indefensible, yet won’t un-endorse him.

6. Trump preparing for a defeat
Over the past week, Mr Trump has ignored attacking Mrs Clinton in favour of making excuses over why he could lose. His party leaders are against him. The election is rigged. The media is biased. Alec Baldwin has it in for him (NBR is disappointed Billy Baldwin was not invited as a Trump debate guest).

That all seems to be laying the groundwork for excuses when he loses on November 8.

Now there are reports he has also been in talks over a possible “Trump TV” conservative news channel. After all, red meat political broadcasting is perhaps the one area where the Trump brand has been enhanced rather than damaged by the campaign.

Republicans will be hoping he does pursue a media venture.

The alternative is he founds his own party or rejoins the Reform Party (home of Ross Perot, who grabbed nearly 20% of the vote in 1992) and takes a big chunk of his supporters with him, ripping the Republican party in two.

Or maybe Donald will just go and pay golf.