WASHINGTON – Viewers of tonight’s final presidential debate should brace for an even more destructive Donald Trump performance, as he carries his desperate scorched-earth strategy to its logical conclusion: disparaging the whole political process he fears will reject him.

His campaign is now clearly in the hands of advisers who are encouraging what Trump welcomes as his “unshackling.” He appears poised to carry his charge of “a rigged system” to the third debate, despite the fact that its moderator, Chris Wallace, comes from the Republican nominee’s favorite media outlet, Fox News.

Ironically, Wallace, as the host of Fox News’ popular Sunday morning political talk show, has been generally free of the glaring partisanship of most of his network. His Fox News colleague Sean Hannity, for instance, has been an undisguised Trump cheerleader.

Wallace, a veteran newscaster for ABC and NBC news outlets before joining Fox News, has maintained more than a modicum of adherence to his employer’s much-mocked slogan of “Fair and Balanced.”

In tonight’s Trump-Clinton debate, he will be under particular scrutiny for how he handles another potential Trump monkey-wrench – the possibility that the Republican will try to discredit the event as part of news media collusion with the Hillary Clinton campaign.

Guiding the Trump campaign now are the notorious conspiracy spinners Stephen Bannon, who was borrowed from the alt-right Breitbart News website, and Roger Stone, a longtime Trump sidekick of boundless slanderous schemes. Not even the sky has been the limit of their audacity.

Since the second debate, and the disclosure of the 2005 video that recorded Trump bragging of his sexual assault on women in the most vulgar terms, the campaign has pivoted to a much broader claim of political conspiracy against him.

In speeches Trump has accused the media of being in cahoots against him not only with the Clinton campaign but with unspecified money interests to exploit the electoral system itself. With inflammatory rhetoric, he has called on supporters to monitor polling places in inner-city precincts with large minority populations, even though such monitoring is already assigned by local election officials.

When it might have appeared that Trump had finally have hit bottom in deprecating his opponent and the political process, he implied at a rally in Portsmouth, N.H., that Hilary Clinton be might on drugs. He suggested that the candidates “should take a drug test” before the debate in Las Vegas because Clinton was “all pumped up at the beginning” of the second debate but seemed to fade at the end.

With opinion polls in various swing states indicating erosion in his support, Trump has begun erroneously claiming he is still leading in them or alleging that the polls are being rigged against him by the news media.

Rather than seek to enlarge the base of support he won so impressively among Republicans in the state primaries, he and his advisers have chosen to fire up that same base with his incendiary rhetoric and allegations of a multifaceted anti-Trump conspiracy.

Trump’s deficit of support among women voters, compounded by a recent wave of women accusing him of sexual assault, has forced him into a defensive crouch. Now he seeks to punch his way out with all manner of wild and irresponsible swings.

In the campaign’s first two debates, Trump took Clinton’s bait and revealed his own thin skin. Subsequently, he has rejected advice to pivot to serious policy discussion and instead has chosen to further foul the conversation by making more allegations against Clinton, the news media and Republicans refusing to support him.

Tonight’s final debate thus promises to bring more of the same from Trump, who seems determined to throw more fuel on the fire. He appears willing to take down the whole house to rally one more time his army of the angry, the discontented and the gullible who have bought into his phony pied-piper tune of “making America great again.”

Editor’s note: Jules Witcover’s latest book is “The American Vice Presidency: From Irrelevance to Power,” published by Smithsonian Books. You can respond to this column at juleswitcover@comcast.net.