Democrats and Republicans alike raised concerns on Wednesday about deep staffing cuts, funding freezes and far-reaching policy changes overseen by U.S. Health and Human Services Secretary Robert F. Kennedy Jr. A bipartisan group of lawmakers questioned Kennedy’s approach to the job, some saying that he has jeopardized vaccine uptake, cancer research and dental health in just a few short months. In combative and at times highly personal rejoinders, Kennedy defended the Trump administration’s dramatic effort to reshape the sprawling, $1.7 trillion-a-year agency, saying it would deliver a more efficient department focused on promoting healthier lifestyles among Americans.