Let’s start with this paragraph from Jonathan Martin in the New York Times.
Yet it would be a sharp rebuke for former Trump administration officials and well-known Republicans to buck their own standard-bearer. Individually, they may not sway many votes — particularly at a time of deep polarization. But their collective opposition, or even resounding silence, could offer something of a permission structure for Trump-skeptical Republicans to put party loyalty aside.
That is the paragraph I want to follow up on, but I do have a longstanding grievance against people who offer a quotation beginning with “Yet…” It always makes be wonder what it refers to. Here is what it refers to: “And polls today indicate that rank-and-file Republicans are squarely behind the president…” 
“Something of a permission structure,” Martin says. Not an expression I have ever heard before, but I know exactly what he means by it.  A whole world of possibilities is called into being by the action of these “well-known Republicans”.
And another piece of this same puzzle if offered by Heather Cox Richardson who, in her June 7 “letter”  says:
The protests, and perhaps even more, the declarations of military leaders, have given anti-Trump Republicans room to buck the president.
The military leaders are saying that President Trump has put the whole structure of military readiness in peril. Nothing about what these leaders are saying sounds partisan or political. Rather, it addresses the primary mode most Americans use it thinking about patriotism, which is using the armed forces to repel attacks by foreign enemies.
Without establishing a strict causal chain, I want to propose that declarations like that of retired Admiral William H. McRaven, who said, “President Trump has shown he doesn’t have the qualities necessary to be a good commander in chief.”
Admiral McRaven, speaking on the 76th anniversary of D-Day said “those wartime leaders inspired Americans with their words, their actions, and their humanity.” In contrast, he said,” “Mr. Trump has failed his leadership test.”
That is about as blunt as it can get. As I look at the structure of Admiral McRaven’s denunciation of Trump, I head Sen. Lloyd Bentsen’s powerful denunciation of Vice Presidential nominee Dan Quayle, “Senator, you’re no Jack Kennedy.”  In both cases, the contrast is carefully prepared (wartime leaders” in the case of the admiral) and then the hammer descends.
And again, without postulating a strict causal chain, I note that President Trump’s support for the Republican candidates in most of the interim elections has not helped them. This is potentially critical. As President, President Trump is head of his party, the party that nominated him as the standard bearer. But the party wants as many Republicans as possible to be elected and each candidate has a sense of what will help and what will harm his chances. A whole fleet of Republican candidates distancing themselves from the leader of their party, trying to enhance their prospects, will be catastrophic for the President.
If the party elders, the George W. Bushes snd the Mitt Romneys, are speaking out about their concerns for what is left of the Republican party and the party foot soldiers are trying to distance themselves from the top of the ticket, it is going to be very hard for the core of Trump’s support to stand firm.
This is what Martin means by “permission structure.” People make decisions and even more make public announcements that they feel they are allowed to make. Broadening the boundaries of the things people are allowed to say about President Trump could be devastating and may be under way. The patriotism card is compromised by the Joint Chiefs; the national intelligence card is compromised by the complaints of recent intelligence leaders; the party elders’ card is compromised by the clear refusal of some to adhere to the leadership and the announcement by some that they are going to vote for a Democrat this time. The Republican candidates will have to find a way to navigate these difficult currents but the permission structure opens a lot of options.
 There are also people who say you should never use a quote ending in an ellipsis, but you have to draw the line somewhere. Trust me, you don’t really need to know what is represented by those three dots and if you do, click the hyperlink and see for yourself.
 I imagine “permission structure” is a version of Peter Berger and Thomas Luckmann’s “plausibility structure,” which is the foundation of their whole sociology of knowledge. A “plausibility structure” is that set of assumptions that allows societies to agree on the shape of the social world they are living in and to decide together, how to approach it. See The Social Construction of Reality if you are interested.
 I feel free to call it a “letter” because her blog is called “Letters from an American,” a play, it seems to me, on J. Hector St. John Crevecoeur’s (1782) Letters from an American Farmer.
 With McRaven, as with Bentsen, the power is in the setup. Bentsen’s rebuke, “You’re no Jack Kennedy” was the fourth item in a series. The whole series went like this: “Senator, I served with Jack Kennedy. I knew Jack Kennedy. Jack Kennedy was a friend of mine. Senator, you’re no Jack Kennedy.”