Sen. Richard Blumenthal criticized Robert F. Kennedy, Jr., the secretary of the U.S. Department of Health and Human Services, after a week that left the Centers for Disease Control and Prevention in a crisis of leadership.

"Robert F. Kennedy Jr. has fired the head of the CDC - the top public health official in the United States - but he is the one who ought to be fired, because he is denying access to vaccines and other potentially life-saving treatment because of his zealotry, his unscientific agenda that he is imposing on the nation," said Sen. Blumenthal.

Sen. Blumenthal says Kennedy Jr. is politicizing public health, undermining his role as a cabinet secretary.

The nation’s top public health agency was left reeling Thursday as the White House worked to expel the CDC director and replace her with Health Secretary Robert F. Kennedy Jr. 's current deputy.

The turmoil triggered rare bipartisan alarm as Kennedy tries to advance anti-vaccine policies that are contradicted by decades of scientific research.

Two administration officials said Jim O'Neill, the second-in-command at the Department of Health and Human Services, would supplant Susan Monarez, a longtime government scientist. O'Neill, a former investment executive who also served at the federal health department under President George W. Bush, does not have a medical background. The officials, who confirmed the change, requested anonymity to discuss personnel decisions before a public announcement.

A flashpoint is expected in the coming weeks as a key advisory committee, which Kennedy has reshaped with vaccine skeptics, is expected to issue new recommendations on immunizations. The panel is scheduled to review standard childhood shots for measles, hepatitis and other diseases.

Two Republican senators called for congressional oversight and some Democrats said Kennedy should be fired. He is scheduled to testify on Capitol Hill on Sept. 4.

Kennedy has not explained the decision to oust Monarez less than a month after she was sworn in, but he warned that more turnover may be ahead.

AP Wire Services contributed to this report.