Sen. John McCain (R-Ariz.) explained his decision to vote against the Republican health care bill early Friday by saying that the legislation “fell short” of “meaningful reform.”

Skinny repeal fell short because it fell short of our promise to repeal & replace Obamacare w/ meaningful reform https://t.co/tZISIvccOO — John McCain (@SenJohnMcCain) July 28, 2017

McCain returned to Washington earlier this week after his brain cancer diagnosis to participate in the Senate’s latest attempt to repeal Obamacare. Along Sens. Susan Collins (R-Maine) and Lisa Murkowski (R-Alaska) and every Democrat, he dealt a blow to those efforts early Friday by casting a vote against Republicans’ so-called skinny repeal bill.

The bill failed in a 49-51 vote in a shocking defeat for Senate Majority Leader Mitch McConnell (R-Ky.). Had it passed, the legislation would have killed several Obamacare provisions, including individual and employer mandates, and stripped millions of people of their health insurance.

The Senate took up the bill Thursday evening despite concerns from Democrats and several Republican senators. Republican leaders, including House Speaker Paul Ryan (R-Wis.), had suggested that, once passed, the House would work with the Senate to improve the legislation rather than sending it straight to President Donald Trump’s desk. However, McCain said on Friday that Ryan’s “statement that the House would be ‘willing’ to go to conference does not ease my concern that this shell of a bill could be taken up and passed at any time.”

McCain told reporters that he thought voting no “was the right thing to do.”

Friday’s vote was a sharp turn for McCain after his votes Tuesday in favor of a motion to advance health care legislation and then voting for a repeal bill, despite having just decried both the legislation and the secrecy surrounding it. That legislation also went down after nine other Republican senators― including Murkowski and Collins, who were viciously criticized by some members of their own party― voted no.

McCain, who was diagnosed with an aggressive form of brain cancer earlier this month and is receiving treatment thanks to his taxpayer-funded health insurance, had been sharply criticized for his votes Tuesday.