The United States Senate has approved former environmental lawyer Robert F Kennedy Jr to lead the federal government’s Department of Health and Human Services (HHS) in the latest closely divided vote over a cabinet nominee picked by President Donald Trump.

Thursday’s vote was narrow, given Kennedy’s history of embracing anti-vaccine views and health-related conspiracy theories.

Fifty-two of the 100 members of the Senate voted yes, all of them members of Trump’s Republican Party. Democrats and independents lined up to offer 48 “nay” votes.

There was one notable Republican defection: Senator Mitch McConnell of Kentucky, a childhood polio survivor and former leader of the party in the Senate. He had previously warned Trump nominees to “steer clear” of “efforts to undermine public confidence in proven cures”.

The leader of the Democrats in the Senate, Chuck Schumer of New York, sought to appeal to Republicans in the minutes before the vote. He called the prospect of Kennedy leading a federal department tasked with ensuring public health “dangerous”.

“ My colleagues on the Republican side, you know the consequences of what you’re doing. My colleagues on the Republican side, you know how dangerous this is. My colleagues on the other side, you know you are not putting your constituents – their health, their families – first when you vote yes,” Schumer said.

Republicans, however, have a small but solid majority in the Senate, holding 53 seats.

And Trump has so far been successful in getting all his nominees to high-level government positions confirmed despite controversies over some of them.

That includes Director of National Intelligence Tulsi Gabbard, who was confirmed on Wednesday despite past statements expressing sympathy for Russia’s “legitimate security concerns” after it invaded Ukraine in 2022.

Defense Secretary Pete Hegseth, meanwhile, was approved in January although the Senate was evenly split, 50-50, over his nomination.

Questions had arisen over allegations that Hegseth had engaged in sexual misconduct and inappropriate behaviour in past leadership roles. Vice President JD Vance ultimately cast the tie-breaking vote.

Kennedy himself faced no shortage of controversy in the lead-up to Thursday’s vote.

His cousin, former US Ambassador Caroline Kennedy, issued an open letter calling him a “predator” who has continued to “lie and cheat his way through life”.

Democrats have also sought to highlight his history of vaccine scepticism and his lack of experience in the medical field.

Although he testified in his confirmation hearings that his own children were vaccinated, Kennedy has publicly spread debunked conspiracy theories linking vaccinations to autism.

During the COVID-19 pandemic, he also made false statements claiming that the virus could have been manufactured to target certain groups.

“There is an argument that it is ethnically targeted. COVID-19 attacks certain races disproportionately,” Kennedy was quoted as saying in the New York Post at a public event. “COVID-19 is targeted to attack Caucasians and Black people.”

In addition, in June 2019, Kennedy visited Samoa shortly before a measles outbreak killed 83 people in the island country.

While Kennedy has denied his trip was about vaccines, an Instagram account showed him embracing a fellow vaccine sceptic during his visit with a caption that included the hashtag “investigate before you vaccinate”.

Samoan health officials, including Director General of Health Alec Ekeroma, have since accused him of helping to spread doubt about the efficacy of vaccinations as a prevention tool.

Republicans nevertheless stood by Kennedy, who was a candidate in the 2024 presidential election. Kennedy initially entered the race as a Democrat, only to announce in October 2023 he would run as an independent.

In August, however, Kennedy ended his presidential bid and threw his support behind Trump, who promised to let him “go wild on health”.

Kennedy, in turn, joined Trump on the campaign trail, offering his own spin on Trump’s “Make America Great Again” slogan: “Make America Healthy Again.”

Republicans on Thursday were quick to dismiss the concerns that have hounded Kennedy’s nomination.

“Contrary to the attacks that have constantly been made on him, he has made it very clear that he will support safe vaccinations and just wants to see that the research on them is done and done well,” Senator Mike Crapo of Idaho said.

He added that Kennedy would bring a “fresh perspective to healthcare”.

“ I agree with him. We’ve got to get into the business of making America healthy again.”

But in his final words before Thursday’s vote, Schumer warned Republicans against following Trump’s lead by approving Kennedy for the high-level health position, calling it “wrong, very wrong”.

He encouraged Republicans to buck the party leadership and vote with their conscience.

“ Today, the question in front of this body is not simply to confirm RFK to run the nation’s health department. The question before us is very simple: Which is more important to you? The health and wellbeing of your constituents or blindly obeying orders?”