a lot of the comments are about the validity/tenability of your position, and while I overall agree with a lot of what is being said (unfortunately, the fact that an adversarial dynamic has been introduced strikes me as the hardest thing to overcome here, though still entirely possible to overcome) here's a few other things to consider:

1. you can lead without being CEO. early on in the life of a company, co-founders often share CEO-like responsibilities on strategy matters and each will separately own / be responsible for their own domain (so in this case, it sounds like you should own the technical part, and your co-founder may own sales, marketing, fundraising, etc.). i think at this early stage the concern regarding leadership can be managed without explicitly changing title - as CTO and co-founder you should have significant influence and decision-making, regardless of title or equity split. if the problem is that the CEO is trying to steer / control things that they don't have an understanding of that you DO have a much better understanding of, regardless of position / equity you should view your job as helping both your cofounder (and any other people on the team) to understand and get behind the strategy that your expertise and experience tell you is right - this is a big part of leadership, getting people to believe in your vision, and the substantive act of succeeding at that should be more important than title, especially at this early stage. don't think to yourself "I'm not the CEO so therefore I can't lead" - you can! especially if you have good logic / basis for your positions. now, if the CEO is intractable, doesn't understand and doesn't want to understand and you can't convince them or the team, I'd say it's not a good match regardless of position (and truthfully, while you may have good reason to consider your cofounder at fault, I'd also argue that the inability to communicate the strategy / expertise is a at a minimum a joint failure in communication, again, good reason to just call it, as understanding each other is key, esp. at this early stage). this is all to say: you should be able to position yourself as the leader on the things you want to lead, regardless of title, esp. at this stage.

2. the board decides who the CEO is, so they should be making the decision (but proceed with MAJOR caution). the board decides who the CEO is, so i hate to suggest this as it will get very messy, but if you really have deep conviction then you may also want to go to the board (which presumably you are part of, so that's good access). since you are VC-backed, there's a good chance you have a VC on your board, and they can act as tie-breaker - if not, you can still rely on investors who own a controlling interest of the investor's class of shares - even if you did a note, whoever is the "lead" or "leads" and have the most sway can help be a tie-breaker here. the board and investors should have the best interest of the company at heart, and if you can really make the case that the best thing is for you to lead, they can arguably help. the problem here may be that if the CEO led the fundraising efforts, their relationship will investors may be stronger (though I could be wrong here), and there's a good chance that going to the board / investors will only accelerate your getting pushed out. of course if you did the fundraising and own those relationships, it should be easier to make a change. the key thing here is to recognize that this is a big escalation, things will move quickly one way or the other (boards are trained to resolve founder disputes with total urgency), so only proceed if you have total conviction and are not afraid to be pushed out entirely over it. I've seen this go many different ways, and while most of the time this blows up the company, it seems like the company would have blown up inevitably because the board maneuverings were just a symptom of deeper underlying issues that could not be resolved. in a small minority of cases, I've seen this work out, usually because one of the founders gets pushed out and the company is able to recover - of course, works out means from the company's perspective, you could of course be the one who is asked to leave. a secondary effect is that if you lose at that level, those VCs will view you as a trouble-maker, and getting funding may be tough for your future projects (from those VCs, but also others as its a small world). again, this is really the highest escalation you can make, proceed with loads of caution and take into account the very serious risks, and view it as a last resort.

3. cofounders need to trust each other. overall, the key issue here seems to be trust: you don't trust that the CEO can lead, and I would assume at this point the CEO may not trust you to accept their position. while the adversarial dynamic may be impossible to reverse at this point, I think more than anything the only way for this to succeed with both of you involved will be if you can both learn to trust each other, cheesy as it sounds this is probably the most important things to have between cofounders, esp. at this early stage (you are both risking a lot betting on the other, trust and good faith is required). again, might be irreparable at this point, but I think now that you've aired your concerns, you can try to guide that into a productive dialogue that establishing trust of the other, acknowledges both your and the cofounders strengths/limitations, and perhaps you can both begin learning to trust eachother more - that being said, at this early stage where you may need to move fast, the process of developing trust will slow the company down and unless you have some serious financial padding (which you may), that time spent on building trust will be what allow your more already aligned competitors' teams (if any) to outrun you. that all being said, if you just don't trust them and you don't think you ever will, then I'd say either leave or think about option 2 above.

sources: worked with execs and boards of many early stage companies around these kinds of issues, as an outside attorney, general counsel and as a business exec.