FOR BUSH, THE REAL BATTLE MAY BE OVER.(MAIN)

Byline: CHUCK RAASCH

Everything in the conventional wisdom and in the campaign script so far says that the Republicans sooner or later have to have a real contest for their presidential nomination next year.

The theory is this: Once the field is cleared to two or three, Texas Gov. George W. Bush won't look so invincible. Steve Forbes' big bucks will kick in, stripping Bush down with a barrage of negative advertising that turns him from a formidable governor to hapless frat boy. Or former Vietnam POW John McCain will go into full battle dress, tapping urges for reform and real heroes.

This theory goes that once Bush is up against a narrowed field, the Republican nomination fight will start to look a lot more like the Democrats', where Vice President Al Gore is in a …