Why is Lindsey Graham clinging to the "no quid pro quo" defense?

Several Republican senators are preparing to shift toward a more plausible defense that there may have been a quid pro quo, but that it wasn’t an impeachable offense. But Graham is still clinging to the argument that there was no quid pro quo. “I still believe that the transcript that I read is not a quid pro quo. Sunderland [sic] is here one day, over here the next,” Graham told reporters in the Capitol earlier this week. “The president of the Ukraine said, ‘no, there was no quid pro quo.’ So, I’m just where I was.” Graham faced derision for saying he wouldn’t read the transcripts of testimony being released, but he did tell reporters he read a “summary” of Sondland’s testimony and noted that Sondland “said he presumed after having talked to people” that the military aid depended on an investigation of Burisma.

So why haven’t Graham and some other congressional Republicans begun making the more plausible “bad but not impeachable” defense of Trump? One reason, Commentary’s Noah Rothman argues, is that Trump won’t yet let Republicans make that argument. (See, for example, acting White House chief of staff Mick Mulvaney’s about-face on whether there had been a quid pro quo.) But even if Trump adjusts the party-line, Graham, appears to have painted himself into a corner where making the “bad but not impeachable” argument would be difficult.