[Sonny M]

I'll tell you right now, if the GOP made lowering the drinking age to 18 as part of its platform, They'd have between 60 and 70 seats in the senate, and probably over 70% of the house, not to mention they would own the governorships, and control this country, without any kind of obstruction for god knows how long.

[GunRunner]

I'm not so optimistic. While adding that to the platform would help the GOP with the 18-25 crowd, the new voters gained from that demographic might not be enough to withstand the backlash from the puritanical and prohibitionist wing of the Republican Party.

The Republicans would be trashed by MADD, a very formidable and powerful lobby who use the same tactics as the Democrats, i.e. supporting an 18 drinking age means you're "pro-drunk driver", the highways would be "bathed in blood" (to quote Illbay). MADD would run ads featuring sobbing parents and remorseful friends talking about how alcohol killed their kids. It would be very nasty, and would help the exodus of the "soccer mom" crowd to the Democrats.