Tribune Co. asked the three finalists bidding for the Chicago Cubs to refine their proposals and may pick a winner as soon as this week, according to two people familiar with the transaction.

Tribune, the newspaper publisher owned by billionaire Sam Zell that filed for bankruptcy protection Dec. 8, is selling the Cubs, Wrigley Field and a stake in a regional sports network to help pay down debt.

The Chicago-based company began the process of selling the Major League Baseball team in April 2007 and has narrowed potential buyers to three groups led by Tom Ricketts, the chairman of Incapital LLC whose father founded TD Ameritrade Holding Corp.; Marc Utay, managing partner of Clarion Capital Partners LLC; and real-estate executive Hersch Klaff.

Previous bids for the Cubs ranged from $850 million to $950 million, a person with knowledge of the process said last month. None of the people wished to be identified because the bidding isn’t public.

Tribune spokesman Gary Weitman said the company doesn’t discuss pending transactions. Major League Baseball spokesman Rich Levin said he wasn’t aware of any timetable for the team’s sale.

The Chicago Tribune said earlier today that its parent could make a decision within a week to 10 days.