President Joe Biden surprised the medical community when he nominated California Attorney General Xavier Becerra to serve on his cabinet as Secretary of Health and Human Services.

While Becerra has a history of fighting for the Affordable Care Act, he lacks any medical background to support his intended role as a top U.S. health official – a factor that some conservatives have taken issue with.

Who is Xavier Becerra?

Biden pledged to make his cabinet reflect "the most diverse Cabinet in history," which he has done through several historical nominations -- but Becerra’s appointment has been one of the president’s more controversial picks.

Under Becerra, the state of California sued President Trump over 100 times on cases focused on immigration, the environment, and healthcare.

"With the NEPA [National Environmental Policy Act] lawsuit, we have sued @realDonaldTrump 100 times," Becerra wrote in an August tweet. "And while we don’t go looking for a fight, we’re prepared to act when the people, resources, and values of California are at stake."

Why Biden chose him

Becerra took on the Trump administration on healthcare and abortion when he led a coalition of 23 states, and the District of Colombia, in challenging the Trump-Pence Administration’s Title X rule in the Supreme Court.

The rule restricted doctors' ability to refer patients for abortion procedures.

"A patient’s medical decisions are between her and her doctor or healthcare provider, not between her and the President or Vice President," Becerra said in an October statement. "Once again, this Administration is playing games with reproductive healthcare, putting politics ahead of patients."

His stance has made him a controversial pick with anti-choice Republicans.

The California Democrat has also appeared in Supreme Court to defend the Affordable Care Act, leading a coalition of 20 states in California vs. Texas after Republican lawmakers sought to dismantle the federal healthcare program.

What do Republicans think about him?

Becerra’s background in fighting for the ACA and abortion rights has led some Republicans to condemn the pick and say he undercuts Biden pledge to bridge the partisan divide.

The most recent condemnation of Becerra came from Arkansas Republican Sen. Tom Cotton, who claimed the California attorney general was "not qualified" to fill the role and accused him of being a "partisan culture warrior," in an op-ed he penned for Fox News Thursday.

"Becerra has targeted social conservatives, religious groups, and others who deny the Democratic Party’s dogmas about life, marriage, and the family," Cotton wrote.

"Any senator who supports his nomination will bear responsibility for his all-too-predictable radical actions in office," he added, suggesting that Biden’s HHS pick could face difficulty getting through his Senate confirmation hearings.

Montana Republican Steve Daines has also voiced his frustration at Biden’s HHS pick, taking to Twitter following the then president-elect’s nomination of the California attorney general last month.

"Xavier Becerra is a disaster for religious freedom and pro-life issues," Sen. Steve Daines, R-Mont., said on Twitter following Biden’s announcement. "He has made his career aggressively pursuing a radical pro-abortion agenda and attacking the religious freedom of Americans who believe in the sanctity of human life."

CLICK HERE TO GET THE FOX NEWS APP

With a split Senate, it is unclear if Biden's pick for HHS Secretary will be able to scrape through the confirmation process, though it is likely. 

The date for Becerra’s hearing has not been set yet.

Howard Kurtz contributed to this report.