The "hostage" approach rarely goes well. People tend to have a thing against hagglers, especially those who have the keys to everything. You may be irreplaceable now, and you'll likely get your raise, but asking for one in such a manner will highlight to management why that's a high priority problem.

You're likely to get a raise without asking in most companies. The bureaucratic levels system is designed as a counter to people forcing salaries beyond their ability. But like someone said, you know your team better than us.