Some are overcomplicating this.
For the most part, the President can do little until the people of Washington actually want him to intervene...and that pressure will eventually come from the bottom up and will be applied, IMHO, most heavily on the Governor. If the Governor does nothing, that will have a consequence and the more outrage amongst the citizenry grows...the better. Intervention from the Fed let's all of these idiots off the hook. So by all means, the President should apply pressure and suggest that he will intervene if necessary...this makes it crystal clear that the Feds are ready and able to restore order and that the one allowing this fiasco to continue is Governor Inslee.
Tennessee, as mentioned, is entirely different because the Governor there will either handle it directly...or will ask for help. Once asked, the Fed becomes a savior...not an oppressor. Further, with public support on the ground, the mission to clear these idiots out because exponentially more manageable.