Several senators now say Rod Rosenstein knew President Trump planned to fire James Comey before he authored his infamous memorandum critiquing the former FBI director's job performance. Does that matter?

Emerging from a classified briefing with Deputy Attorney General on Thursday, Sen. Claire McCaskill, D-Mo., and Sen. Dick Durbin, D-Ill., both said that Rosenstein revealed he knew the president planned to fire Comey before writing the memo. (Sen. Marco Rubio, R-Fla., pushed back on those claims.)

The memo, repeatedly (and erroneously) referred to as a "recommendation" by the Trump administration, was cited by Trump in his notice of dismissal to Comey and then cited by his spokespersons as the animus for his firing.

In a press conference on Thursday, Trump also cited the FBI's decision to send a letter correcting key details of Comey's testimony regarding emails on Anthony Weiner's laptop as a reason for his decision, along with Comey's performance during that testimony itself.

Under normal circumstances, the Deputy Attorney General sending a letter casting strong doubt on the FBI director's ability to do his job, and that director being corrected on basic facts of a major investigation by his own department, would be reasonable explanations for their firing.

But the administration's story has changed so many times that no explanation is credible.

Trump himself provided yet another reason last week as well, telling Lester Holt, "when I decided to just do it, I said to myself, I said 'you know, this Russia thing with Trump and Russia is a made-up story, it's an excuse by the Democrats for having lost an election that they should have won."

Sure, a combination of all these factors could have compelled Trump to pull the trigger, and that would be reasonable, but the administration's changing story leaves the impression that the White House orchestrated a sloppy misinformation campaign to obfuscate the president's real motivation.

We still do not know whether Trump asked Rosenstein to write the memo as a way to generate a justification for Comey's firing. That Rosenstein knew Comey was to be fired before he wrote the memo obviously lends credence to that theory.

But if the president knew Rosenstein, who is well-respected by people in both parties, believed it was wise to fire Comey, what's wrong with him using that as a justification for doing so?

Again, if that is indeed what happened, and if the administration had been open and straightforward about it from the outset of this controversy, it's very possible the White House could have avoided the news erupting into a scandal.

Emily Jashinsky is a commentary writer for the Washington Examiner.