Robert F. Kennedy Jr. was set to start meeting Republican senators Monday as the vaccine skeptic launches his contentious confirmation bid for health secretary. President-elect Trump’s controversial cabinet nominee headed to Capitol Hill for the first of more than a dozen planned meetings with GOP senators as he addresses questions about his views on vaccines. Kennedy will also face tough questions about his stance favoring abortion rights and controversial positions on food safety and other health issues. It was unclear if Kennedy will be accompanied by Aaron Siri, a key adviser who filed a petition in 2022 to revoke approval for the polio vaccine, which public health officials credit with eradicating the disease in the U.S. Siri, one of the most prominent lawyers in the anti-vaxxer movement, has reportedly been interviewing officials for possible senior jobs in a Kennedy-run Health and Human Services Department. Senate Republican leader Mitch McConnell, who survived polio as a child, says Kennedy should “steer clear” of efforts to discredit the polio vaccine. “Efforts to undermine public confidence in proven cures are not just uninformed — they’re dangerous,” McConnell said in a statement Friday. Kennedy and his allies say he is not opposed to vaccines but simply wants to subject them for more rigorous medical testing or give people the option of choosing whether to get vaccinated. RFK Jr. has also said that he believes vaccines cause autism, a conspiracy theory that doctors say has been debunked by countless scientific medical studies. Critics say Kennedy’s baseless questioning of vaccine effectiveness could lead to the reversal of long-standing vaccine mandates for children attending public school, in turn opening the door to the return of countless killer diseases. Aside from vaccines, RFK Jr. has been harshly critical of the American health care system and food companies, suggesting that millions of Americans are being poisoned by unhealthy foods and poor health care treatment. He also broadly backs abortion rights, a position that puts him at odds with most Republicans in Congress. Some anti-abortion figures like former Vice President Mike Pence have criticized him although most have held their fire in deference to Trump. RFK Jr. has strong backing from Trump, who wields virtually unchallenged power within the GOP for now. But his controversial positions could spark opposition from corporate lobbyists for the industries involved, who amount to some of the biggest bankrollers of Republican lawmakers. Like other nominees, RFK Jr. needs support of at least 50 senators to win confirmation, meaning he could likely afford to lose the votes of no more than three GOP senators. Trump was once a strong supporter of vaccines and boasted that he saved millions of lives by pushing for the rapid development of the vaccines that ended the COVID pandemic. But with right-wing fury over COVID restrictions driving anti-vaxxer sentiment, the president-elect has vowed to let Kennedy “go wild” on vaccines and the American health system.