Among the current group of candidates for POTUS, which candidate worries you the most? Take into consideration both their positions and their electability. As a Democrat, I find Scott Walker the scariest of the bunch. Bush and Rubio would be bad, but I don’t think that they would be terrible. Given how he’s run Wisconsin, however, Walker is downright scary. I also see him as somewhat electable, and my guess is that when (not if) Trump drops out, that Scott Walker will probably be the one to benefit the most. How do you all feel?
Bush is the scariest because i think he is the only one with even a remote chance of winning.
I agree with the OP on Walker. He’s been a professional politician practically from birth (he won his first public office at, what, 22?), and seems to be very, very good at the job of getting elected. His policies, on the other hand, are awful. In particular, he seems entirely hostile to the concept of education as anything but preparation for work, and his concept of “preparation for work” seems quite narrow.
Given that the House will certainly remain in GOP hands, and the Senate is, at best, a tossup, I think any Republican could do extreme and lasting damage to the country. If Walker were elected, though, it would likely mean the GOP as a whole had done very well in 2016. That would make me quite nervous for the future.
I find none of the Democrats scary, except the one who isn’t running: Liz Warren. Sanders is honest and straightforward, so he doesn’t bother me. His views bother me, but I can live with a progressive who doesn’t lie or deceive the public about his intentions. I don’t think Warren is above that.
But if I have to choose from the existing field: Lincoln Chaffee. Chaffee is soft and ineffectual. He doesn’t scare me, but the consequences of electing such a weak man in a dangerous world are a little scary.
For me it’s Jindal, easily. A man who should know better, does know better, and will say whatever is expedient to please his demographic. An educated man pandering to the ignorant.
President Walker, Perry or Jindal - Gasp!
Crane
For me it’s Cruz. I hope he’s not electible, but 20+ million fellow Texans thought he was so great they voted for him (well, 20M didn’t actually vote for him, but you know what I mean).
Cruz here too. He’s got the skillz, as his success in becoming the effective Speaker of the House while still a freshman Senator attests, and that’s what makes him actually dangerous. But he doesn’t have any principle behind it other than ambition, not even the principle of pretending to be responsible while doing nothing but rabble-rousing and sheer vandalism.
Walker, for the reasons mentioned in posts 1 & 3.
Seconded.
I can see the OP’s point about Walker, but even though he has done well winning elections in his home state I don’t the he would do well nationally so that reduces concerns I might have about him.
The rest have little to no chance of getting close to the nomination.
Jindal doesn’t scare me; he entertains me. 
He has no shot at the nomination and for the life of me I cannot figure out why he’s bothering. As others have said, he’s a pretty bright guy, contrary to his failed attempts at coming off as an authentic trog to please his base, so he has to know his running is a futile exercise at best.
Perry doesn’t scare me because he’s an absolute dunce. Too bad he doesn’t realize it.
Huckabee doesn’t scare me because although he’s not Perry stupid, he’s not too bright.
Fiorina doesn’t scare me, or anyone else for that matter. She’s a nonentity.
Graham, Kasich, and Pataki don’t scare me because their base of support is tiny and the Tea Party will stop them dead in their tracks.
Christie doesn’t scare me because the GOP base considers him a liberal Republican. He’ll never make it out of the primary alive.
Carson doesn’t scare me because he’s just this cycle’s Herman Cain.
Santorum doesn’t scare me because he’s a living punchline.
Rubio doesn’t scare me because being a Hispanic Republican guarantees nothing, even with the Cuban heritage, especially as he is not that smart to begin with.
Trump doesn’t scare me because he’s, well, Trump. Seriously, he doesn’t even want to be president, does he?
For some reason, ¡Jeb! doesn’t scare me, even though he is likely to win the Republican nomination.
Paul doesn’t scare me, probably because I think he has little chance at the nomination and he doesn’t strike me as completely nuts.
Cruz scares me, not because of his chances of becoming president, which I believe are pretty low, but because he has proven he has the will and ability to damage this country for the most inexplicable purposes.
Walker, now he scares me. I think he could actually win the nomination, although I do believe sanity will prevail and ¡Jeb! will get it.
Walker - because in addition to the reasons given above, and his potential electability, he also seems to be the most compliant sock puppet for the people who control the purse strings - like the Koch brothers. I think he’ll do anything his donors want him to, even moreso than most politicians. I don’t know if I even have any real evidence of that, to be honest; it’s just the really strong impression I get from him. Not to mention the damage he’s done to education and the working class in Wisconsin will take a long, long time to heal.
among serious contenders: Scott Walker. He’s a true ideologue on both economics and social policy, plain and simple. Among all of them, Rick Santorum, especially because of how huge a bible thumper he is.
Even tho I lean Democratic, I cannot say I’d vote for Sanders if he somehow got the nomination. I don’t like ideologues.
Mike Huckabee. He wants to turn the country into a Christian Caliphate.
Rubio scares me the most.
Although I expect Bush to be the nominee, Rubio has a non-negligible chance of catching fire as a fresh, charismatic alternative to Bush who is acceptable to the establishment. (I just don’t see it with Walker.) Of any leading candidate, I see Rubio as the most likely to corner himself into committing the US to a major Middle East war. His recent comments on Iran provide a good preview of what foreign policy stance to expect from a President Rubio.
He strikes me as a rudderless tenderfoot who’s learned that he gets handsomely patted on the head every time he does that hawkish thing he does, and so he keeps doing it without any appreciation for the consequences of his positions were they to become policy.
Let’s consider the product (dangerousness if elected) * P(elected if nominated).
The difference between the candidates with respect to the first factor is pretty small, because the GOP Congress will be passing the same legislation without regard for who’s President, as long as it’s a Republican, and the President will sign that legislation, regardless of who it is. Though I’d give a bit of an edge to Walker among those who might have a chance of being elected. The way he’s going after the University of Wisconsin shows a desire to tear down things we libruls like, just because we like them.
So it mostly comes down to the second factor (electability if nominated). Walker and Jeb! are the only ones I’m worried about. If he’s in the spotlight for very long, Rubio will reveal himself to be only somewhat smarter than Palin, and somewhat dumber than Dubya, so I’m not worried about him. And I think Walker’s got a better chance than Jeb of rallying every last possible GOP base voter and getting them to vote.
So I’m most scared of Scott Walker.
Jeb Bush was a founding member of PNAC. His statements about Iraq indicate the tiger hasn’t changed his stripes.
I was going to say something about how I grew up in the same kinds of churches as Scott Walker, and he scares me as an oblivious-to-consequence privileged evangelical-Republican goober who would tear apart the legacies of the labor movement and the New Deal just because he thinks that’s what’s he supposed to do. He looks, even at his age, like some of the more oblivious college lads I know from gaming.
Now saying that feels like piling on.
OK, Huckabee is scary because he seems superficially like a good guy, and he could easily win a second term even as he quietly gutted the country’s institutions. Like Reagan or Clinton, I guess. 
I am deeply concerned about that amount of anti-union sentiment that the Republicans have been able to foster, and the degree to which Walker is riding that tide. Given that the Supreme Court has a 5 to 4 split in the pocket of big business and will in all likelihood rule against the unions in Friedrichs v. California Teachers Association.
If Walker gets in he likely attempt gut all labor regulations and any right to collectively organize and I’m not sure that anyone would be able to stop him.
The anti-union sentiment is mainly directed at public sector unions, an idea even liberals used to oppose until they realized it was good for campaign donations. But as a policy matter, it’s still a bad idea. Illinois is in deep trouble for making promises to their public employees that they’ve known for decades they couldn’t keep, and when the state tried to renege, the courts slapped them down. Now they’re just screwed. Once taxpayers get the bill, public employee unions and government in general are going to get a lot less popular in that state.