U.S. President Donald Trump attends the Greek Independence Day Celebration at the White House in Washington, U.S., March 18, 2019. REUTERS/Carlos Barria

(Reuters) - President Donald Trump will nominate a Washington attorney, Christopher Landau, to be the next United States Ambassador to Mexico, the White House Press Office said on Monday.

The nomination comes at a time of strained relations between the neighbors amid trade disputes, Trump’s complaints about undocumented immigrants crossing the border, and his efforts to build an extended border wall.

Roberta Jacobson, the previous U.S. ambassador, stepped down in May, joining a list of senior U.S. State Department officials to resign during Trump’s presidency.

Landau, now a partner at the law firm of Quinn Emanuel Urquhart & Sullivan LLP, was a law clerk for Supreme Court Justice Antonin Scalia, who died in 2016, and then for Justice Clarence Thomas, both considered court conservatives.

The White House described Landau as a constitutional and appellate attorney who has briefed and argued appeals before the Supreme Court, Federal courts of appeals, and State appellate courts.

He previously headed the appellate litigation practice at the firm of Kirkland & Ellis LLP.

In 2017, Landau served a three-year term as a member of the Judicial Conference Advisory Committee on Appellate Rules, the White House said.

No formal diplomatic experience was mentioned in the White House statement, which said Landau is fluent in Spanish.

Landau could not immediately be reached for comment.