Last week, there was speculation that Chief Justice John G. Roberts Jr. had originally planned to strike down the Affordable Care Act’s individual mandate, before changing his mind and ruling to uphold the mandate as a tax. Now, CBS News’s Jan Crawford reports that Roberts did switch his vote, and that the court’s conservatives tried for a month to win him back to their side.

In the court’s private vote after oral arguments in March, Roberts sided with the other four conservative justices to strike down the law, the report said. But, it said, about six weeks later, while writing the decision that would invalidate the health-care law, he changed his mind.

There were countless news articles in May warning of damage to the Court - and to Roberts’ reputation - if the Court were to strike down the mandate. [...]

It was around this time that it also became clear to the conservative justices that Roberts was, as one put it, “wobbly,” the sources said. [...]

Roberts then withstood a month-long, desperate campaign to bring him back to his original position, the sources said. Ironically, Justice Anthony Kennedy – believed by many conservatives to be the justice most likely to defect and vote for the law – led the effort to try to bring Roberts back to the fold.

There were some signs of a shift in the four conservatives’ dissent. The dissent read more like a majority opinion. There was no engagement with Roberts’s opinion, and the dissent includes a long passage on whether the remainder of the health-care law could be severed from the mandate — as if the mandate had been struck down.

However, according to Crawford, the dissent was not originally written as a majority opinion. Sources told the news organization that the dissent ignores Roberts not out of “sloppiness” but because “the conservatives no longer wished to engage in debate with him.”

In a city where leaks are commonplace, the Supreme Court is unusually good at keeping secrets. Orrin Kerr, a legal blogger at the Volokh Conspiracy, notes that “a clerk who leaked this and is identified has likely made a career-ending move.”

But numerous conservatives wrote at the time that the liberal media were trying to intimidate the chief justice. The New York Times’s Linda Greenhouse hypothesizes that they got some sort of inside information.

“I wondered at the time whether they had picked up signals that the chief justice, thought reliable after the oral argument two months earlier, was now wavering,” she wrote, “and whether their message was really intended for him.”