I remember that some people called Romney's speech after the rally his, "tear down this wall" moment. I think Romney handled the incident well, but his bold stand against Russian meddling in the 2016 election is probably the best thing he's done. After hearing that Russia had hacked the election, Romney immediately moved to condemn Putin and implement sanctions against Russia with wide bipartisan support. This helped to take the wind out of Biden's sails and push Romney over the finish line in 2016. Romney has been far from perfect as President, but I do respect the good things he's done and standing up to Putin was one of them. Unfortunately Trump doesn't feel the same way. Just today he tweeted out that, "POTUS is very UNFAIR to Russia! Meanwhile, our borders go UNPROTECTED! MAGA!" I'm really sick of his silly online rants, which unfortunately will only get worse if he runs for President.
A recent Gallup poll showed that Trump would get 14% of the vote if he makes a third party bid for President in 2020. If he does, the GOP will be in a world of hurt next election cycle.