Outcry on Right Over Bush Plan On Immigration
Conservative Republicans vying for votes in Congressional races across US are mounting opposition to Pres Bush's plan to grant temporary legal status to millions of illegal immigrants; Jim Oberweis, Republican who is running for Senate seat in Illinois, has become leader in widening revolt against Bush's plan; Bush hopes to revamp immigration system widely viewed as broken and to re-establish his credentials as compassionate conservative--particularly with Hispanic and swing voters; plan has left party divided; Republicans say it is unlikely that legislation supporting plan will be introduced in 2004; Oberweis photo (M)