The Ted Cruz incident with McConnell involved the Export-Import Bank (story here).
Now, Ron Johnson is reportedly concluding McConnell committed a breach of trust by privately telling moderate senators that the Medicaid cuts in the healthcare bill won't actually occur, as reported here.
The current Republican bill in the Senate appears dead as four senators in the Republican caucus have said they don't support it. With a 2-seat majority, only 3 defections are tolerable (the tie-breaker vote is cast by the Vice President, Mike Pence).
When all is said and done we might find out that the loss of support is all intentional and orchestrated in order to save the Senate from having to vote on the issue again at all. The nay-sayers may be handsomely rewarded at some future date while getting to please their constituencies.
Remember, Republicans generally don't believe in anything except for what is. In other words, maintaining the status quo is their objective. They are pragmatists who are willing to accept progressive creations once passed, like the income tax, Social Security, Medicare and now Obamacare, and will defend those programs no matter how they became law.
Lighting their hair on fire for anything is completely out of the question, including for the constitution.
The only thing that will save us now is a meteor strike on the Senate chamber while they are all in session.