Jesse Jackson Jr. favored as Sen. Obama’s replacement. U.S. Rep. Jesse Jackson Jr. is a favorite among likely voters to fill the Senate seat being vacated by President-elect Barack Obama, a poll indicates. A Zogby telephone poll conducted last week shows that among 10 possible candidates, 21 percent say they think Democratic Gov. Rod Blagojevich should appoint Jackson to the seat when Obama leaves it vacant in January to become president, United Press International is reporting. The only other potential candidate to get double-digit support was Tammy Duckworth, a former Democratic congressional candidate from Chicago who accompanied Obama in a reef laying ceremony in the Midwest city on Tuesday.  Fourteen percent of respondents said she should be appointed. In two prospective Senate races, Jackson would defeat Republican Congressman Ray LaHood by a 50 percent to 31 percent margin, the survey shows. The poll of 802 likely voters statewide has a margin of error of plus or minus 3.5 percentage points.