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Watch the final presidential debate Wednesday on CNN at 9pm ET

Las Vegas CNN —  

For Hillary Clinton and Donald Trump, it’s time to begin the closing arguments.

Both nominees enter Wednesday’s presidential debate – the final showdown of the election season – with historically high unfavorability ratings, and need to convince undecided voters why the country would be worse off with their opponent in the White House.

Trump enters the match-up in his weakest position yet in national polls and is losing ground in key battleground states. And he is making perhaps his most outlandish argument yet – that the 2016 election is rigged to help Clinton win. Clinton, meanwhile, will have a fresh set of questions to answer around newly released hacked emails and fresh revelations about her use of a private email server at the State Department.

If the last two debates are any indication, Wednesday night promises to be contentious, theatrical, and unpredictable. Here’s what to watch:

Will Trump insist the election is ‘rigged?”

With his national poll numbers sliding and Democrats making a strong play for Republicans strongholds like Arizona, Trump is issuing a fresh warning to supporters: If I lose, don’t believe the results.

His message that the election is “rigged” and that the political system is skewed to guarantee a Clinton victory, shows Trump taking his distrust of the media and propensity to fuel conspiracy theories beyond what even he has exhibited previously.

It’s a scorched-earth strategy that the Republican nominee appears likely to stick to before millions of viewers on Wednesday night, even though many of Trump’s fellow Republicans have repudiated talk of a rigged vote.

Trump’s critics argue that his insistence that the election is rigged simply underscores the nominee’s growing pessimism about his Election Day prospects.

At a news conference in the White House Rose Garden on Tuesday, President Barack Obama mocked Trump for “whining before the game’s even over.”

There is “no serious person out there who would suggest somehow that you could even rig America’s elections,” Obama said.