Stocks remained slightly lower in early-afternoon action Friday as uncertainty over the presidential election and the looming fiscal cliff outweighed improved economic data. The Nasdaq and Dow Jones industrial average were each down 0.2%. The S&P 500 fell 0.1% after edging higher in early trading. Volume was down 8% on the Nasdaq and 1% on the NYSE compared with the same time Thursday. Rentech Nitrogen Partners (RNF) bucked the market's downdraft,