Hire a vocalist who can BE a front man. There are very very few player/singer combos who have the charisma to be a real front man. There are a ton of talented singers to get onboard all over the country, or world really.

Don't suggest taking it over. You blow up any relationship and one or both of you will crash and burn out of the band. I've been in a couple groups where this scenario played out, as a lot of singers who suck think they are great, and it always ends badly.

Get a real front man and avoid this topic in this manner.