What, if any, risks are the politicians (like Susan Collins) running by saying that they cannot support Trump. If he were to win, would Trump try to punish her?

You can bet on it.

Trump has never learned the “keep your friends close and your enemies closer” lesson.

Going with the hypothetical if he wins…

It would not surprise me if he would use his new-found power to publicly shame these folks, or to hurt them politically and/or socially.

What kind of risk are these people taking?

For some, it’s a matter of conscience, or at least loyalty to the Republican party traditional values. I also think it might be an attempt to distance the “down-ticket” Republican candidates, especially the Congress, governors and state legislatures, from the Trump doctrine, which is far from the traditional, or even neo-con values.

Paul Ryan and the “early movers” took a risk, but I think it was calculated. Being on the right side of a landslide can distance them from the loss altogether in people’s minds. It gives them some say in the new direction because “you don’t want Trump to happen again”...

In Ryan’s case, he’s the highest profile, young, and has aspirations of his own. He’s played it strategically all along I think.

I was hoping for a big break up, maybe even a third party, but it looks like everyone is hedging their bets already so they can just say “we never liked that guy anyway” and move on with the same platform they started with, just more restrained in what they say.

He will certainly lash out regardless of the outcome of the election, and would attempt as much retribution as possible.

But there isn’t really much he could do. If he wins and the Reps keep the Senate, there still isn’t much he can do. She is a sitting Senator, and she can block much more of his efforts than he can punish her.

I wouldn’t be surprised if he started disappearing his detractors.

Republican party traditional values

Trump values ARE traditional Republican values.

You can’t pretend that 50 years of appealing to racist, resentful whites is a deviation for their TRUE selves.

These people are at very little risk for the simple reason that there are just too many of them. It’s analagous to the reason our government did not prosecute draft dodgers after Vietnam. Trump would actually be unable to govern were he to actually attempt to ostracize his critics. Things have now reached the point that rejection of Trump is the standard for a demonstration of competence. Those few defying the blatantly visual evidence with the claim that the emperor is fully clothed do so at their eternal peril. Any endorsement of this level of stupefying incompetence marks those doing so as either cognitively impaired, or proclaiming to the world “I have no integrity”.

I’m certain Trump would try to punish his detractors.
But, honestly, how do you effectively punish 75% of the population of the United States. The world?

And personally? I believe that the politicians that revile Trump are closer to 90%+. I think most of his retribution would be blocked, and it’s even possible that the rewards for having the balls to say what everyone else is thinking could be great.
“I refused to support Donald Trump” is going to be a powerful message for years to come, regardless of the outcome in November.

He will lash out at anyone any time. It’s futile to try to pacify him.

I agree with @ibsturbro that those who are standing up as against to him will be the “winners” in the future.

He will thank anyone who helps split the vote away from Hillary Clinton. The only way he will be elected is if people piss away their votes on third party wanna-bes. He will owe them a strong debt of gratitude. But he doesn’t like paying his debts, so I wouldn’t hold your breath.

The phrase ‘lash out’ is mentioned several times. I think that perfectly describes what will happen. Win or lose, he will most likely explode like a volcano.

Or the 2nd amendment people will have a shooting spree. See today’s headline.

Or the 2nd amendment people will have a shooting spree.

Back in my day, Republicans kept their treason behind closed doors – killing the Paris peace talks, keeping Americans hostage in Iran, outing CIA agents and their networks.

Harumph!

He can pressure political action committees (PACs) and others who may endorse a candidate not to support the politicians who oppose him. That will mean less money in their campaign budgets that they would have receive from endorsements from the PACs.

Of course, if he doesn’t win, he have less political clout than Mitt Romney.

Sure, I would expect him to behave much like Chris Christie would.