Two sources told NPR that the attorney general got into a “shouting match” with Utah Republican Sen. Mike Lee, a key figure in opposing Liu’s bid. A spokeswoman for Barr declined comment on the heated conversation with a lawmaker from his own political party. For his part, Barr issued a statement filled with praise for Liu and insisting, “We will all benefit from her universally-regarded expertise and dedication to public service” in her role as an adviser to him.

Four lawyers familiar with the matter said the stumbling block for Liu was a broader concern about her conservatism — specifically, her stance on women’s reproductive rights. Interest groups had begun drafting letters to senators about their fears that Liu would not support restrictions on abortion. Another key factor: Earlier in her career, Liu had an affiliation with the National Association of Women Lawyers, which sent a letter opposing the nomination of Justice Samuel Alito to the Supreme Court.