Sen. John McCain delivered an unexpected “no” vote in the early hours of Friday morning that helped defeat an amendment to repeal portions of Obamacare, and said later in a statement that he did so because he wasn’t confident that the bill eventually would not become law.

The bill, which removed only parts of Obamacare, was being pitched to Republicans as a vehicle to get something out of the Senate and into a conference with the House where senators hoped it will be improved into a more comprehensive replacement of Obamacare.