U.S. private equity firm TPG has emerged as a front runner to buy Dow Chemical's Styron plastics business, Wall Street Journal said, citing several people familiar with the matter. TPG's rival Apollo Management, which was one of the contenders for the Dow unit, is fading from contention, the paper said.

Dow, the largest U.S. chemical company, put Styron up for sale in July and said at the time the unit could fetch $1 billion to $2 billion. Dow has said that it hopes to sell the unit, which makes polystyrene, rubber and latex, by the end of the first quarter. The paper said a deal could be announced as early as this week.

Dow Chemicals and TPG could not be immediately reached for comment by Reuters.