History suggests it is very difficult to beat a sitting President. I believe the smart Republicans decided to wait until 2016. Hell, I was willing to bet that Chris Christie's entire family voted Obama so he could run for President in 2016 instead of 2020.

Then again, I though those same Republicans ducked out in 2012 because they thought Hillary would tear them up. I bet they were as surprised as I was when Obama beat her in the Primaries.

The ones who opposed Mitt in the primaries could not use Bain Capital against him, it would have made them appear anti-business.

They could not use his opposition to the Auto Industry Bailout because they opposed it too.

They could not use his $87,000 medical deduction for a horse, because he had not released his taxes.

In the Primaries, Mitt stayed on message, was very conservative, provided very few details in order to win the South. Or as the Republicans call it, "the least informed voters".

Mitt also beat the heck out of his Primary opponents with personal attacks. And Mitt had big Super-PAC $$$ going into negative ads against his opponents

Staying on message really came back to hurt him in the election when he tried to flip to the center to try and win over Independents and Democrats. It destroyed any credibility he might have had - which was very little thanks to his resistance to releasing his taxes.

The Romney campaign also failed to understand the Undecided / Independent Voters in the Swing States. They are mostly ex-Republicans, thanks to Dubya. Romney's people thought if they won a majority of that group, it would signal a victory. But the Independents, while mostly voting Romney turned out to be a net loss.

And his opposition to the Auto Bailout killed him in Ohio.

P.S. I am registered as an Independent voter.