Bill C-51 is all but law. It just needs approval from the Senate, with a vote expected to come on Tuesday. The bill criminalizes promoting and advocating terrorism, and expands the powers of the Canadian Security Intelligence Service.

But as the vote approaches, opposition is coming from a new angle. A group who describe themselves as "principled conservatives and libertarians" posted an open letter to Prime Minister Stephen Harper, calling the bill "reckless, dangerous and ineffective." They warn him that Bill C-51 would divide conservatives and that it could cost him the election.

The first signature on the letter belongs to Sheldon Clare, president of the National Firearms Association.

This interview has been edited for clarity and length.

In this letter to the Prime Minister, it says Bill C-51 "compromises the security of everyone in an effort to deal with a few." Are you saying that Bill C-51 could make Canadians less safe?

I don't think that's a fair characterization. I think what we have to be really cognizant about in this particular legislation is not the expectation of improved or enhanced public safety that is promised by it. It's really the danger of harm that could arise from this bill were it to go forward and be abused by a subsequent government of ill intent. I don't think this government has ill intent. I don't think the next government would have ill intent, but a government down the road may well make use of some of the tools provided for in this bill. And I don't think a lot of Canadians really support an increased sort of statism with regards to our police powers.

But what does that increase in power mean for gun owners? What is the threat that could affect their interests?

Well, a lot of concerns that firearms owners have are around privacy. I think our position is one of wanting to make sure that firearms owners are not being targeted in any way or that they have to be looking over their shoulders or be afraid for being perfectly innocent ordinary Canadians who just happen to own and use firearms responsibly.

So are you concerned that a future government with these powers could create a phantom gun registry? Is that what you're saying?

Well, I think C-51 does much more than that. It enables an entire way of dealing with potential threats. And I think aspects of things like the ability to protest freedom of speech and so on are things that are more of concern to our members, given that the more people become aware of C-51, the more concerned they get about it. And I've got to say, we were able to say to the government that we had some concerns about privacy. We did see the government make some amendments to this particular bill before they started putting it through the house. And we were comfortable that we did get some of what we wanted.

It doesn't sound like that when you read this letter, because here's what the letter says to the Prime Minister: "We believed you when you told us that you were going to allow amendments to this bill... The problems in C-51 could have been fixed... Instead, you chose to attack those sounding the alarm as leftist ideologues." That's strong language. Has Stephen Harper burned bridges with your constituency?

No, I don't think he's burned any bridges. We're all about building bridges. We've tried to have our say with the Prime Minister's people about our concerns. We felt that some of those concerns were listened to, but other aspects have not been listened to. And I really think that this bill was prepared a bit hastily. And I don't believe that it really has had the sober second thought that it should have. I'm hoping that the Senate will really have had a good kick at it.

We're talking about a law that will give powers of disruption, the sharing of information between agencies, a lack of oversight. How will those powers possibly be - in your mind - abused to hurt the members of your organization?

One of the things I think you have to be careful of when you start letting agencies share information and you build a great strong police state, is you need to go back and realize: what can they do now about bad behavior? We've already seen that they can stop people who want to go off and serve with ISIS overseas. They've already been able to arrest them and they've already been able to charge and prosecute them.

I'm just really concerned that, although that's the stated aim, the effect of it might be something much worse. And what that effect is, I don't know. But I do know that when you have governments that have more and more power and control over their people and there is more and more gathering of information, they're going to use that information. Because, frankly, the threat of terrorism in Canada is really not one of the great pressing problems of our age. It's really a lot of other issues that are facing our country today. The economy is probably the most dramatic issue. And I look at this in some respects as a distraction from things that really should be getting the attention of government and moving forward an agenda that works well for all Canadians.

The NFA was scheduled to testify to a parliamentary committee over Bill C-51 and your organization canceled. That was controversial, what happened?

Well, we didn't really want to be used as a stick, for example by the NDP, to be hitting the government over the head. We were in in talks with the government about our concerns of C-51. We felt that we'd made our point to the government and had some pretty good meetings, probably much more time in meetings than we would have that in just the hearings. We were optimistic we would get our say. But the result seems to be disappointing.

That disappointment is reflected in this letter. So this letter is maybe more of a stick, but you're a willing partner in it.

We've been a member of that coalition for some time and we're one of the largest groups in it. And the fact of the matter is, our members are concerned about privacy. They're concerned about the government being too strong and I think most small "c" conservatives don't like big government and this looks like big government legislation

So you think this is a piece of flawed legislation. Why do you think the government is so determined to make this law?

I think that there was some idea that terrorism is this huge threat that needs to be dealt with. They've certainly had certain high-profile incidents that have happened, terrible incidents. Soldiers getting run over with cars, or the incident on Parliament Hill with young Cpl. [Nathan] Cirillo being killed at the National War Memorial. That event shocked every Canadian. When you have these high-profile incidents, there's always the pressure that government needs to do something. But basing legislation on an emotional reaction is a terrible memorial to leave.