Want a really tough job? Try secretary of homeland security.

The Department of Homeland Security comprises a sprawling enterprise touching on many of the federal government’s duties to keep the nation “safe, free and prosperous.”

Homeland security is a 24/7/365 mission. And when done right, there are few tasks more thankless.

Every day, Americans get to live their lives unmolested by terror and unobservant of those charged to protect them. When the red lights start flashing, the department becomes the center of attention and scrutiny.

While our confidence has waxed and waned over the department’s 15-year history, what’s apparent is that when Homeland Security was well led, it has been a department that served the American people well.

Even in his short tenure as secretary, John Kelly proved a great steward of the homeland security mission. He was the right leader for all the right reasons.

Even after he left, the department continued to reflect his style of get-the-job-done leadership. Eliane Duke has served well as acting secretary, and the department has delivered—most notably in its disaster response mission dealing with an unprecedented number of major storms and the horrific wildfires in California.

The department has gained uniformed praise with the notable exception of the recovery efforts in Puerto Rico, where criticism stemmed as much from raw partisanship as it did a realistic appreciation for how quickly efforts could be put in place to help millions of Americans at risk.

Tit-for-tat feuding aside, the reality is that without a massive and prompt federal response, there would not just be shortages in running water, electrical power, and long lines for supplies—there would have been an unprecedented loss of life that would have greatly dwarfed Katrina.

What is notable is that despite outside attempts to turn a determined disaster response into a political albatross to hang around the neck of the administration, department officials shrugged off the controversies and focused on their job.

It’s not just FEMA at work—the whole department is in the field dealing with the aftermath of four major disasters at the same time.

It has been reported that on Wednesday, the president will announce the nomination of Kirstjen Nielsen as the next secretary of the department. Nielsen served as Kelly’s chief of staff at Homeland Security and currently in the White House.

There is no tougher person for the job than Nielsen. First of all, she passed the Kelly test. Working effectively for a tough boss alone makes her someone who can stand the fire in the kitchen.

But more than just being tough, she is smart and knows the ins and out of the mission of national security as well as anyone.

Those who have worked with her over the years respect her great expertise and knowledge in cybersecurity and other important technical and legal aspects of securing and protecting the nation.

Nielsen also served on the presidential transition team, where she helped assess the department’s strengths and weaknesses and formulate action plans to boost inter-department cooperation, Human Resources, and management—improving the nuts and bolts that have long hampered the department’s effectiveness.

She has had successful careers in both government and the private sector. She knows how the real world works, how to get things done—and most of all, she will be ready at the times the nation will need the department most.