President Donald Trump has pulled his controversial pick to be the U.S. Surgeon General, Casey Means, after she failed to win enough votes in the Senate to be confirmed.

On Thursday, Trump posted on his social media network, Truth Social, that Means' nomination had been withdrawn and that he would instead nominate cancer radiologist and Fox News contributor Nicole Saphier.

Means, a health influencer with no active medical licence, had drawn criticism from some senators due to her views on health, and vaccines in particular.

In his posts, Trump also lambasted Louisiana Republican Senator Bill Cassidy, a trained physician whom he blamed for blocking Means' nomination.

Means' nomination has not advanced since her confirmation hearing in the Senate in February. During the hearing, she declined to say whether babies should receive vaccines and questioned established science about whether vaccines cause autism.

"I believe vaccines save lives. I believe that vaccines are a key part of every public health strategy for any infectious disease," she told lawmakers at the time.

But she stood behind the idea of autonomy in medical decision-making throughout the hearing.

A Stanford-trained doctor, entrepreneur, and health influencer, she had been seen as an ally of Health Secretary Robert Kennedy, whose own views on vaccines have alarmed some lawmakers, including Republicans.

On Truth Social, Trump argued that Sen Cassidy "has stood in the way" of her nomination with his "intransigence and political games". He also called for Louisiana to vote him out of office.

He went on to praise his latest selection, Dr Saphier, as "a STAR physician who has spent her career guiding women facing breast cancer through their diagnosis and treatment while tirelessly advocating to increase early cancer detection and prevention, while at the same time working with men and women on all other forms of cancer diagnoses and treatments".

"She is also an INCREDIBLE COMMUNICATOR, who makes complicated health issues more easily understood by all Americans," Trump added.

In 2020, Saphier published the book Make America Healthy Again: How Bad Behaviour and Big Government Caused a Trillion-Dollar Crisis. She also has a podcast called Wellness Unmasked.

Saphier - who works as a radiologist at Memorial Sloan Kettering Cancer Centre, Monmouth - is now Trump's third choice to lead the 6,000-employee US Public Health Service.

His first choice was Janette Nesheiwat, a doctor and former Fox News contributor who faced criticism from one of Trump's advisers over her COVID views and questions about her credentials.