“If this thing does fall all apart on the shoals,” said one former top Hill aide, “maybe the difference is the lack of good messengers. On a nailbiter, you don’t want any margin of error.”

And critics in both parties said Mnuchin and Cohn may have helped create one…

Some Republicans on Capitol Hill have started to distance themselves. House Speaker Paul Ryan earlier this month asked the White House not to send Mnuchin to the Hill to talk with Republican lawmakers about the bill, according to two people familiar with the discussions – though Ryan has praised the Treasury secretary’s ability to improve the legislation itself.