Joe Biden plans to nominate California attorney-general Xavier Becerra for secretary of health and human services, which would add another Latino member to the president-elect's diverse cabinet, US media reported.
During Mr Becerra's 12 terms in Congress representing Los Angeles, he was an outspoken advocate of Latino rights.
He was also a vigorous defender of former president Barack Obama's signature health care programme. The policy, colloquially known as Obamacare, has been much attacked by President Donald Trump and Republicans.
NBC, The New York Times and several other news organisations reported on the plan to nominate Mr Becerra, citing anonymous sources close to the president-elect.
Mr Becerra, 62, was elected as California Attorney General in 2016, succeeding Vice President-elect Kamala Harris after she was elected to the US Senate. Mr Becerra was the first Latino to hold that office.
While in office, he also defended the immigrant rights programme DACA in front of the Supreme Court.
According to the Times, Mr Becerra's nomination comes after complaints from the Congressional Hispanic Caucus about a lack of Latinos in the incoming cabinet.
Mr Biden has announced Cuban-born Alejandro Mayorkas as his pick to head the Department of Homeland Security.
If confirmed, Mr Becerra would be tasked with leading the department amid the coronavirus pandemic that has killed over 282,000 in the US.
For the third day in a row, the United States on Saturday notched a record number of coronavirus cases in 24 hours, reaching nearly 230,000 new infections, according to a tally by Johns Hopkins University.
Mr Biden has stressed that he would strive for diversity while choosing staff for when he takes office in January.
In addition to Becerra, other firsts include the first female Treasury secretary, the first female head of intelligence and the first Latino chief of Homeland Security.