As Donald Trump builds his administration, it’s important to distinguish between his legitimate decisions on personnel and policy — even those that differ substantially from mainstream ones — and the scarier actions that need to be resisted by everyone committed to democracy.

Take the first big announcements on filling jobs at the White House. As the new chief of staff, Reince Priebus, the Republican National Committee chairman, is not the worst possible choice.

But the president-elect also has chosen Steve Bannon as chief strategist and senior counselor. By announcing the two appointments together, Trump is suggesting the two may have comparable clout.

Thus, Bannon is about to become one of the most influential people in the country.

Bannon is a longtime professional bigot, as documented by the Southern Poverty Law Center among others. When both the Anti-Defamation League and the Council on American-Islamic Relations — two groups that have clashed with each other — immediately condemn the same thing, you know something is not normal. And, in this case, it is also not acceptable.

Bigotry isn’t just immoral. It puts democracy at risk by threatening the equal citizenship of those who are targeted.

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Trump’s threats against the media and against his political opponents, by undermining legitimate opposition, are in the same category.

Win or lose, this is a battle worth fighting. But how?

White House staff positions, unlike cabinet and other executive-branch appointments, are not subject to the advice and consent of the Senate. That’s how it should be: These crucial positions are responsible only to the president, whereas the top officials in executive-branch departments and agencies have to answer to Congress as well as the president.

But outside opposition can raise the cost, perhaps higher than even Trump is willing to pay. Organized groups and individual constituents can demand that every member of Congress, in both parties and both chambers, go on record as supporting or opposing the selection of Bannon.

It’s true that presidents are entitled to the staff they want, but members of Congress routinely offer their opinions on such selections — and so those opposed should push hard to get a response.

If Bannon is to be defeated, the Republican senators who opposed Trump in the election might be the key.

Though the Senate can’t directly block Bannon, individual senators can place a “hold” on one or more Cabinet or executive-branch nominees and refuse to budge unless he is removed from consideration. Honoring these holds is at the discretion of the majority leader. If Senate Majority Leader Mitch McConnell, R-Kentucky, tries to move ahead despite the objections, then Democrats and some Republicans could vote down Cabinet picks until Trump relents.

Even if Republican senators like Nebraska’s Ben Sasse and Arizona’s Jeff Flake, who would not support Trump in the campaign, won’t fight, opposition from organized groups could still be enough to defeat this selection. Trump might be initially emboldened by this dissent, but then could grow impatient.

Even if unsuccessful, this is a fight worth having. It can put Trump on notice immediately that the political system will push back if he follows through on subverting democratic norms.

And, yes, this is one time when it would useful to clarify where everyone stands. A lot of Republicans resisted Trump’s nomination, and a fair number were willing to stand against him even in the general election. Many, naturally, will support a lot of the policies he signs into law. Forcing a fight on Bannon will give them an early opportunity to demonstrate that they still oppose the anti-democratic excesses — and keep anti-Trump liberals and conservatives on the same side of a fight, even as they part ways over (say) Obamacare and taxes.

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Yes, the battle to keep this man from having a formal role in government is a long shot. But it’s worth fighting.

Bernstein is a Bloomberg View columnist covering U.S. politics.