In what's believed to be one of the earliest-ever vetoes in a new governor's term, Democrat Mark Dayton late Thursday rejected a bill by Republicans to pare down part of the state's six-billion-dollar budget deficit.  Dayton warned the measure, which would have continued predecessor Tim Pawlenty's cuts in state aid to cities and counties, would drive property taxes and impact middle-income Minnesotans.  The governor says his budget plan, due on next Tuesday, will focus on the income tax at the top income level.  Some analysts warn the session could be a repeat of 2005 or worse when state government partially shut down after the governor and legislature deadlocked over the budget.