President-elect Donald Trump has chosen Republican Gov. Kristi L. Noem of South Dakota to serve as homeland security secretary, according to people familiar with the selection who spoke on the condition of anonymity to discuss a decision not yet made public.

Trump is off to a rapid start rolling out his picks for key administration jobs as he prepares for a return to the White House in January. House Republicans, who are close to claiming a majority in their chamber, plan to hold a news conference Tuesday. Senate Republicans plan to elect leaders Wednesday.

Homeland security secretary is a crucial role, given Trump’s focus on border security.

As homeland security secretary, Noem would lead a sprawling federal bureaucracy with a $60 billion budget and more than 230,000 employees.

The role is key to Trump’s domestic policy agenda, especially given his pledge to deport millions of undocumented immigrants and impose a crackdown at the U.S.-Mexico border.

Perhaps no issue animated Trump’s campaign against Vice President Kamala Harris more than border security. He has already named a “border czar” to oversee the program: Tom Homan, who was acting director of Immigration and Customs Enforcement during Trump’s first term.

Stephen Miller, a former Trump adviser known for his hard-line immigration stances, is also set to return in a new Trump administration as Trump’s deputy chief of staff for policy.

Noem has served as South Dakota governor since 2019. She stood out early on for her refusal to implement restrictions related to the coronavirus pandemic in her state.

Noem was initially viewed as a possible running mate for Trump in his comeback campaign. But her prospects seemed to dim after she recalled in a book published in May that she shot and killed a family dog because it was “untrainable” and aggressive.

Noem remained a campaign surrogate for Trump, who ultimately picked Ohio Sen. JD Vance as his vice-presidential candidate.

This story will be updated.