Sen. Bill Cassidy (R-La.) criticized Health and Human Services Secretary Robert F. Kennedy Jr.’s decision to cancel a $500 million investment in lifesaving mRNA vaccine research aimed at protecting the U.S. against future viral threats.

“It is unfortunate that the Secretary just canceled a half a billion worth of work, wasting the money which is already invested,” Cassidy wrote in an online post on Wednesday following the HHS announcement. “He has also conceded to China an important technology needed to combat cancer and infectious disease.”

“President Trump wants to Make America Healthy Again and Make America Great Again. This works against both of President Trump’s goals,” the senator added.

Kennedy wouldn’t be in Donald Trump’s administration without Cassidy’s support for his confirmation earlier this year. The physician, who has served in the Senate since 2015, swallowed his concerns about RFK Jr.’s long record of anti-vaccine views under pressure from Trump’s MAGA supporters who have an eye on his reelection next year. Cassidy has worked hard to get back into Trump’s good graces despite facing a GOP primary.

The Louisiana Republican, who serves as the chair of the Senate health committee, said in February that Kennedy assured him he would not dismantle the nation’s vaccine safety systems; the HHS secretary has moved to do exactly that.