Opinion | I Quit the First Trump Administration. Principled People Must Serve in the Second.

In 2018, as a member of the first Trump administration, I anonymously published an opinion essay in The Times warning that President Donald Trump was unstable and a danger to “the health of our Republic.”

At the time, I was a senior official in the Department of Homeland Security grappling with Mr. Trump’s worst excesses. (I eventually became chief of staff for the department.) I quit the administration in 2019 and openly campaigned against Mr. Trump, a decision that resulted in a flurry of threats to my physical safety that required me to relocate to a safe house with an armed guard.

My advice to fellow conservatives ahead of Mr. Trump’s return to the presidency is not to run from him, as some might say they should. Instead, I urge them to join him, as I once did.

Republicans with integrity cannot turn away from the difficult years ahead. They should step forward and serve in the executive branch out of dedication to the principles that hold this country together, however tenuously.

I can assure future staff members that working in a Trump administration will not be as turbulent as the media makes it out to be. It will be rockier.

When I worked at the Department of Homeland Security, Mr. Trump’s unpredictable impulses often upended the department. I was in the room when he demanded that we withhold federal aid from disaster-stricken states that had voted against him. I listened as he proposed partnering with Russia on cybersecurity. And I saw him lose control in a fight with North Korea because of personal insults — a crisis that sent us scrambling to prepare for a possible nuclear war.

We would cancel international summits to race back to Washington to talk him out of clearly unlawful decisions — at the border, on federal spending — or to soften the edges of reckless actions. Sometimes it worked. Sometimes it didn’t. Eventually, many of us quit and went public with our criticisms, resulting in what is presumably the largest group of former officials in U.S. history to oppose a president they had served.

Alas, it did not prevent Mr. Trump’s return to power.

Soon Mr. Trump will arrive at the White House not as an outsider, as he did for his first term, but as a man who sees his stunning re-election as vindication — a mandate to wield the presidency more assertively than before. He will return with fewer restraints and greater resolve.

So why would I encourage anyone to join this political melee? Because America needs principled conservatives in this administration — not as a “deep state” but as a conscience.

Let me be clear: Mr. Trump won a sweeping comeback victory. When he takes office, lawful presidential policies should be heeded by executive branch appointees and civil servants alike. This is how our system works. It is not the job of those in his administration to defy him as a matter of course. But it is their job to follow the law and, if necessary, keep him from breaking it.

Believe me, he will try, whether deliberately or through sheer carelessness.

Mr. Trump needs people around him who understand the functions of the executive branch and have a moral compass, especially in the realm of national security. While many Reagan- and Bush-era conservatives have been driven from the party, there is an array of seasoned G.O.P. figures capable of stepping into these posts and leading agencies with a steady hand.

Broadly speaking, Republicans should go into his administration to do what we’ve always said we would: keep government limited and prevent abuses of power. They might end up being the only reason Mr. Trump holds back from doing something unlawful — or at least, if they fail, they will be the only people to tell their fellow Americans the truth.

If this doesn’t sound like an inspiring reason to serve, you’re right. It is not. Would-be appointees of the next Trump administration should be cleareyed about what they are walking into.

I want them to advance the conservative agenda, yet I know the reality. They will be subjected to controversy everywhere they go. Their policy wins will be overshadowed by their boss’s transgressions. Family members will see them as guilty by association, friends will disown them and large swaths of the public will revile them. While they should hold their heads high, they should have their resignation letters handy at all times because, sooner or later, they will most likely quit or be fired, and like many ex-Trump officials, they could struggle to find work.

But along the way they might save the Republic, too.

The suggestion may sound grandiose. Yet if Mr. Trump does what he says, he will test democracy’s guardrails — flouting his cabinet, the courts and Congress to do things the law may not allow.

On the day that John Kelly, the former Marine Corps general, was sworn in as the White House chief of staff in 2017, many of us gathered around him and Mr. Trump in the Oval Office. A grinning Mr. Trump asked him to speak to the group, evidently eager to see the general become his own lieutenant.

Mr. Kelly chose his words carefully. He reminded everyone in the room that in America public servants don’t swear an oath to a man. If they did, we’d be living in a despotism. They swear allegiance to the Constitution, he said firmly. Mr. Trump’s face fell and Mr. Kelly put his hand on the Bible as a judge recited the oath.

Conservatives of conscience must join the second Trump administration. And on Day 1, they, too, should make the Constitution their only lodestar.

Miles Taylor (@MilesTaylorUSA) was a senior official in the Department of Homeland Security from 2017 to 2019.

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