WASHINGTON (Reuters) -Senate Republicans on Thursday confronted U.S. Health and Human Services Secretary Robert F. Kennedy Jr. over concerns about vaccine policy, while largely dismissing questions about the independence of a Federal Reserve board nominee, at separate congressional hearings that showed the shifting balance of power between Republican lawmakers and President Donald Trump. 

Kennedy appeared before the Senate Finance Committee a week after the Trump administration fired Susan Monarez as director of the Centers for Disease Control and Prevention over her refusal to follow Kennedy's limitations on vaccine availability, which she believed were unscientific. Four other top CDC officials resigned in protest, raising warnings from experts that the health of the American public could be at risk.

Republican Senator Bill Cassidy, who chairs a separate committee overseeing health policy, grilled the top Trump healthcare official about the cancellation of $500 million in COVID vaccine contracts, while citing examples of doctors and cancer patients who have been unable to obtain the protection against the potentially deadly disease.  

"I would say, effectively, we're denying people vaccine," concluded Cassidy, a physician who was key to getting Kennedy confirmed to Trump's cabinet this year.

"Well, you're wrong," Kennedy responded. 

The proceedings marked a dramatic change of tone for congressional Republicans, who have usually worked to enact Trump's policies, confirm his nominees and defend his administration officials. In recent days, a handful of Republicans have pushed back on a unilateral Trump move to cancel congressionally approved government funding, calling the action illegal.  

Senator John Barrasso of Wyoming, the chamber's No. 2 Republican who is also a physician, expressed concern that vaccines for other diseases, including measles and hepatitis B, could be in jeopardy under Kennedy's leadership, potentially raising the risk of reversing decades of progress in public health.

"I've grown deeply concerned," Barrasso said. "If we're going to make America healthy again, we can't allow public health to be undermined." 

Republican Senator Thom Tillis questioned the veracity of Kennedy's earlier commitments to empower scientists, his views on development of the COVID-19 vaccine and the firing of Monarez as CDC director.      

"I don't see how you go over four weeks from (employing) a public health expert with unimpeachable scientific credentials, a long-time champion of MAHA values, caring and compassionate, and brilliant microbiologist, and four weeks later fire her because at least the public reports say she refused to fire people who worked for her," Tillis told Kennedy, referring to the health secretary's Make America Healthy Again slogan.

Other Republicans steered clear of vaccines and turmoil at the CDC, at times blaming Democrats and the news media for circulating politically charged misinformation about U.S. healthcare. 

"Under this administration, HHS has placed patients at the center of the healthcare system, empowering them with the tools and information they need to create a healthier future," said Senate Finance Committee Chairman Mike Crapo, an Idaho Republican.

FED NOMINEE'S ASSURANCES ACCEPTED

Meanwhile, White House economic adviser Stephen Miran, Trump's nominee to fill a vacancy on the Fed board that unexpectedly opened last month, came before the Senate Banking Committee for his confirmation hearing after weeks of attacks by Trump on Fed Chair Jerome Powell and an unprecedented effort to fire board Governor Lisa Cook.

Independent analysts and some Democrats say Trump chose Miran for the Fed board as part of a drive to gain control of the Fed and force the central bank to lower interest rates. Senator Elizabeth Warren, the committee's top Democrat, warned that Miran would "take an axe" to the central bank's independence if he joined the Fed. 

But Republicans, who are moving to confirm Miran quickly, accepted the nominee's assurances that he viewed Fed independence as paramount. 

"One of the things I like about you is that you're clear, you're consistent and you've been honest," Banking Committee Chairman Tim Scott told Miran.

Republican Senator John Kennedy asked Miran whether he was personally responsible for Trump's public comments or would be "Donald Trump's puppet." To the latter question, the nominee replied: "Not at all. I'm very independently minded." 

"We are going to hold you to that," said Kennedy, a Louisiana Republican.

At the Senate Finance Committee hearing, some Republicans defended the health secretary against attacks by Democrats, including allegations that he lied to the committee in earlier testimony by pledging not to take actions that would discourage Americans from accepting vaccines.

Crapo refused a Democratic request to have him testify under oath. 

"This committee's unwillingness to swear this witness is basically a message that it is acceptable to lie to the Senate Finance Committee about hugely important questions like vaccines," said Senator Ron Wyden, the panel's top Democrat. 

The hearings occurred as some Senate Republicans are beginning to chafe at Trump's efforts to extend his control over federal spending by rescinding previously allocated funding. 

Lawmakers say those efforts could endanger hopes of a bipartisan effort to avert a government shutdown on October 1. 

Some Senate Republicans have aired criticism of the administration and opposed its legislative priorities on the chamber floor. But Trump's grip on the Republican Party has cut short serious opposition up to now.