Health Secretary Jeremy Hunt has been accused of holding "anti-science views" and promoting "primitive social attitudes" by a leading Liberal Democrat in the Lords.
Lord Taverne launched his attack on Mr Hunt over his backing of homeopathy and recent call to cut the abortion limit to 12 weeks.
At question time, Lord Taverne criticised Mr Hunt for "his opposition to research into hybrid stem cells" and "stirring up the abortion debate".
He urged health minister Earl Howe to persuade him to make a "public-reassuring statement that he will not use his position as head of the health service to promote the kind of anti-science views and primitive social attitudes which are normally associated with the American Tea Party".
His charges brought cheers from the Opposition benches.
Lord Howe said Mr Hunt would be well aware of public comments on his recent statements.
"He is entitled to his personal views," Lord Howe said. "As regards the Government's position, it remains the responsibility of local NHS organisations to make decisions on the commissioning and funding of healthcare treatments, such as homeopathy."
Labour spokesman Lord Hunt of Kings Heath said: "The secretary of state should at least show some discretion when he comes to make statements on these issues, in the sense that he is head of the Department of Health and the NHS."