On Wednesday, Donald Trump announced that Breitbart News executive Stephen Bannon would run his campaign.
The most significant aspect of last week's Conservative Political Action Conference was not President Trump's repetitive rant against the news media and fake news. It was the public unveiling of his chief strategist, former Breitbart News CEO Steve Bannon, who came out of the shadows to explain his philosophical takeover of the Trump administration.
With the bark off what he called his "deconstruction of the administrative state," Mr. Bannon revealed his intention to capitalize on Mr. Trump's uncomplicated gut appeal to the working-class anger and discontent that put him in the Oval Office.
Its most destructive aspect is Mr. Bannon's harnessing of the new president's simplistic pitch of "America First," that old right-wing battle cry, to challenge the whole concept of Western unity after World War II and the Cold War.
The president himself -- always more focused on Trump First than any deep ideological view of the world beyond -- has become a tool with which Mr. Bannon may steer the world's leading democracy off the course of Western collective security and onto one of narrow national economic self-interest.
By the same token, Mr. Bannon has co-opted Mr. Trump's lapdog-like White House chief of staff, former Wisconsin state and then national committee chairman Reince Priebus, to help annex the old conservative heart of the Republican Party.
Mr. Priebus boasted at the CPAC celebration that Mr. Trump in only a month in office was able to unify the Republican family. Heretofore over many years, the old GOP had taken pride in its leadership of the Western community, including the European Union, holding fast through the collapse of the old Soviet Union.
Now, however, Mr. Trump has castigated other North Atlantic Treaty Alliance members for having lagged on their financial commitments. His secretary of defense, Gen. Jim Mattis, has been obliged to assure them of the Trump administration's continued fealty to NATO.
Old establishment Republicans also cling to their suspicions of Russia under Vladimir Putin, and of Mr. Trump's efforts to improve relations with him, despite the Russian leader's notions of restoring empire in seizing Crimea and imperiling Ukrainian independence.
But Mr. Bannon at the same time has signaled his intent to anchor American sovereignty as the centerpiece of the new presidency both at home and abroad. At CPAC, he cited Mr. Trump's withdrawal from the Transpacific Trade Partnership as one of the "most pivotal moments in modern American history." Mr. Trump echoed him, saying "the core conviction of our movement" was that the U.S. "will put its own citizens first."
Mr. Bannon also has enlisted Mr. Trump in his deep hostility to American journalism as he advances his concept of economic nationalism. In dubbing the media "the opposition party" -- excepting, of course, the Trump-friendly Fox News network -- he has labeled most reporters "corporatist " and "globalist" and adamantly opposed to Mr. Trump's supposed focus on the needs of neglected average Americans.
Why Mr. Bannon, after operating behind the curtains since joining the Trump campaign, suddenly decided to adopt a public persona is something of a mystery. Mr. Trump's decision to make him a member of his National Security Council, with no significant high-level background in the security and intelligence fields, obviously has elevated his role and influence as the key White House insider.
In the critical days ahead, it appears that Mr. Trump will continue in his favorite role as cheerleader-in-chief, providing the rhetorical red meat menu of promises to the faithful, more attacks on the press and his own "alternative facts" to keep them energized.
Meanwhile, Mr. Bannon will focus on the ideological and philosophical aspects that he intends to drive Mr. Trump's presidency on the path of addressing the more personal needs and interests of the "forgotten men and women of America."
The Trump approach undeniably proved formidable in the 2016 campaign. Whether the Bannon course will prove to advance Republican Party unity or impede it is an open question.
Jules Witcover is a syndicated columnist and former long-time writer for The Baltimore Sun. His latest book is "The American Vice Presidency: From Irrelevance to Power" (Smithsonian Books). His email is email@example.com.