Stephanie Grisham, who has served as first lady Melania Trump’s fiercely loyal communications director, will succeed Sarah Sanders as White House press secretary, the White House said Tuesday.

The move was first announced by Trump in a tweet and later confirmed by White House officials. In addition to succeeding Sanders, Grisham will also take on the duties of White House communications director, a job that has been vacant since March.

“She has been with us since 2015 - @potus & I can think of no better person to serve the Administration & our country,” the first lady said in her tweet.

President Trump announced two weeks ago that Sanders, whose tenure was marked by controversy and questions about her credibility, would be leaving at the end of the month. In a tweet, he said she would be returning home to Arkansas.

Grisham, 42, is one of Trump’s last remaining campaign aides serving in the White House. Before becoming the first lady’s communications director in March 2017, she worked in the West Wing as a deputy to Trump’s first press secretary, Sean Spicer.

Grisham previously was a local political operative who had worked on Mitt Romney’s 2012 campaign for president.

“During the campaign she developed a good relationship with the president, and that’s carried through,” Sanders said of Grisham in an interview late last year. “She has developed a great amount of trust from both the president and the first lady, which is a pretty high commodity here. There aren’t a lot of people who have a lot of regular interaction with both of them.”

In a tweet Tuesday, Sanders said she is “sad to leave the WH, but so happy to leave our team in such great hands.”

“Proud to have another mom and a great friend in this role,” Sanders added. Grisham is a single mother of two boys.

Grisham’s appointment comes at a pivotal time in Trump’s tenure, as he increasingly turns his attention to seeking reelection next year.

The job of press secretary has been transformed under Sanders, who rarely holds White House briefings, traditionally a staple of the job. It remains unclear whether Grisham will seek to revive the once-daily give-and-take with reporters.

During her tenure with the first lady, Grisham has developed a combative reputation with the press as well as inside the administration.

In preparation for Melania Trump’s first solo trip abroad, to Africa last fall, deputy national security adviser Mira Ricardel clashed with members of the first lady’s staff. Upon their return, Grisham and the first lady’s chief of staff, Lindsay Reynolds, approached then-White House Chief of Staff John F. Kelly about the issue.

When he took no apparent action, Grisham spoke directly to Melania Trump, who in turn spoke to her husband privately. Then, when still nothing happened, Grisham suggested to the first lady a different strategy: Without giving the West Wing warning, Grisham put out a statement: “It is the position of the Office of the First Lady that she no longer deserves the honor of serving in this White House.”

Within days, Ricardel was out of the White House.

Grisham has also not hesitated to offer stern advice to the press.

When the first lady visited a shelter for migrant children in Texas a year ago, a media circus ensued over the army-green jacket she wore with the words “I really don’t care. Do U?” written on the back in white.

Grisham soon took to Twitter with an admonishment: “If media would spend their time & energy on her actions & efforts to help kids - rather than speculate & focus on her wardrobe - we could get so much accomplished on behalf of children.”

Before the Romney campaign, Grisham created her own small public relations firm, worked for AAA Arizona, the Arizona Charter Schools Association and Larson public relations, which represents education reform clients across the country.

Others in contention to replace Sanders included her principal deputy press secretary, Hogan Gidley.

Josh Dawsey and Sarah Ellison contributed to this report.