Democratic lawmakers are calling on President-elect Joe Biden to pick ambassadors with the same focus on diversity he used to fill his Cabinet, according to a letter obtained by Axios.

Why it matters: The demand for more minorities representing the country abroad shows how some Democratic interest groups will hold Biden to his diversity pledge throughout the federal government, including his sub-Cabinet, U.S. attorneys and diplomats.

Reps. Joaquin Castro and Veronica Escobar wrote this weekend in a joint letter to Tony Blinken, Biden's nominee for secretary of state, to discuss the "grave disparities in racial and ethnic minority representation in the Foreign Service."

• Escobar (D-Texas) said, “Ambassadorial appointments, Foreign Service and Civil Service employees must reflect our broad diversity and the full breadth of American ingenuity and intellect."
• Castro (D-Texas) wrote: "People are policy — and the diplomats who represent the United States to the world should reflect the diversity of the American people."
• While under-representation predated President Trump, he appointed white people to more than 90% of his openings, Foreign Policy reported in 2018.

The big picture: The congressional call for ambassadorial diversity will complicate the ambitions of big-dollar Democratic donors, who hope to be rewarded for their fundraising prowess with postcard embassies in Western Europe, South America and the Caribbean.

• Those plum posts have traditionally gone to donors or politicians representing about a third of the roughly 190 available ambassadorships.
• Sen. Elizabeth Warren (D-Mass.) railed against the bipartisan practice of turning donors into diplomats during the campaign.
• The president-elect was noncommittal on the campaign trail, saying, “I’m going to appoint the best people possible,” AP reported.

By the numbers: Trump picked more political ambassadors than his immediate predecessors, naming non-State Department employees like Gordon Sondland — a West Coast hotelier and GOP donor who served as ambassador to the European Union.

• Trump tapped political ambassadors for 44% of his nominations, with the remaining 56% going to career Foreign Service officers, according to the American Foreign Service Association.
• Under President Obama, 30% of his ambassadors came from the political or donor world, leaving some 70% for the diplomatic corps.
• For President George W. Bush, the ratio was 32% to 68%.

Go deeper: The State Department has struggled to achieve greater minority representation in its upper ranks, with a Government Accountability Office report last year showing people of color make up 14% of the senior officers in the Foreign Service and 24% of the overall workforce.

• Out of 189 U.S. ambassadors serving abroad last summer, three were Black and four were Hispanic career diplomats, according to the American Academy of Diplomacy.
• "The President-elect and Secretary-designate Blinken know that the power of our example is strongest when we are leveraging diversity — especially among women, people of color, LGBTQ+, and other under-represented groups — at all levels, including senior leadership," said Ned Price, a transition spokesman.
• Biden's team looks "forward to working with Congress on this task," Price said.