A Trump administration official who pushed the idea of releasing undocumented immigrants into “sanctuary cities” has moved to the powerful Office of the White House Counsel, according to two sources familiar with move. She’s a rising star in the White House, and an ally of Donald Trump’s senior policy adviser.

In her new post, May Davis will work on immigration and domestic policy, giving top policy adviser and immigration hardliner Stephen Miller another ally in the counsel’s office.

“I can confirm May works and reports to the White House Counsel’s Office, and continues to be a very valued member of the White House,” a White House official told The Daily Beast. “We look forward to her contributing to the President’s agenda in a legal capacity in her new role.”

Davis, a Harvard Law graduate and immigration hawk, is poised to play an important part in helping guide some of Trump’s most consequential policy moves, particularly on executive orders that are screened and closely examined by the counsel’s office. On Wednesday, the president again claimed that his administration was “seriously” looking at ending birthright citizenship, a potential executive order that would likely fall under Davis’s portfolio.

Three administration officials described Davis as an ally of Miller, with one saying she was a staunch supporter of the “zero tolerance” policy that resulted in the separation of migrant families on the U.S. southern border. Since the early days of the Trump campaign, Miller has driven Trump’s hardline immigration stances and has helped craft some of his most controversial policies, including his travel ban on people from seven majority-Muslim countries.

“May is a total professional and one of the most level-headed people in the White House,” said a former White House official who worked with Davis. “She knows the ins and outs of the administration and will be a huge asset as the administration navigates various policy proposals in the upcoming months.”

Davis previously served as a White House policy coordinator and largely dodged media attention during her time in the administration––with one prior exception. In an email The New York Times reviewed, Davis floated to DHS officials that they release detained undocumented immigrants into so-called sanctuary cities.

“The idea has been raised by one to two principals that, if we are unable to build sufficient temporary housing, that caravan members be bused to small- and mid-sized sanctuary cities,” Davis wrote, noting the White House had not reached a final decision on the idea.

Her route to the White House Counsel’s Office has been circuitous. After the Senate confirmed Kelly Craft as Trump’s United Nations ambassador last month, Davis was apparently tapped as her chief of staff, according to the State Department directory viewed by The Daily Beast. (She was listed as chief of staff as recently as Tuesday.)

In the White House, Davis has participated in the Miller-led Immigration Strategic Working Group, according to White House communications reviewed by The Daily Beast. The group includes more than 30 Trump administration officials who gather regularly to work on immigration policy and enforcement. Participants include officials from the Justice Department, the Department of Homeland Security, Immigration and Customs Enforcement, the National Security Council, and the State Department.

Davis will work alongside Steven Menashi, another lawyer in the White House Counsel’s Office who has also participated in Miller’s working group. Menashi is currently awaiting confirmation to be a judge on the Second Circuit Court of Appeals.

She previously worked in the office of the White House staff secretary, serving under Rob Porter, who left early last year after his ex-wives accused him of physical and emotional abuse. During that period, Miller felt Porter’s office interfered too much in the speechwriting process, according to a person familiar with the situation. In the time since, Miller and Davis grew to be allies in the Trump administration, particularly on immigration policy, multiple sources noted.