Some Republicans actually believe the biennial clich? that the present [midterm] election is the most important of their lifetime — and that the future of the republic depends on a new GOP majority that can rein in President Obama. So a White House hopeful seen as doing anything but advancing the cause would invite opprobrium.
I think this has it exactly right. Most Republicans believe that stopping the Obama administration and Democrat-dominated Congress from advancing any more of its reckless, Left-wing agenda is the most important task facing the nation, by far. Accomplishing this objective requires a focused, all-hands-on-deck approach from a broad center-right coalition. If any individual decided to suck up political oxygen by unnecessarily creating the huge distraction of a presidential announcement, it would be considered an unforgivable act of selfishness that would more than offset any perceived benefit of announcing first.