Voters re-elected three incumbents to the East Baton Rouge Parish School Board on Tuesday, but forced Dec. 6 runoffs in three other races, in the process sending incumbent Mary Lynch packing after just six months on the board, according to complete but unofficial returns.

Lynch’s defeat means business-supported board members are likely to have at least a bare 5-4 majority on the board that takes office Jan. 1. Local business leaders supported her opponents, Jennifer Andrews and Mark Bellue, particularly Bellue, in the race in District 1; Bellue fell 189 votes short of winning outright and consequently will face Andrews in the runoff.

A divided electorate also resulted in runoffs in districts 5 and 8.

In District 5, a battle of incumbents awaits between Evelyn Ware-Jackson and Jerry Arbour since both polled well short of the 50 percent mark, though Ware-Jackson was slightly ahead. Arbour opted to run in District 5 rather than District 9, where he was placed thanks to redistricting. W.T. Winfield came up short in his bid to return to the board he served on from 2008 to 2010, while newcomer Patty Merrick lagged in fourth place.

In District 8, incumbent Connie Bernard fell 455 votes short in her bid to earn a second term Tuesday. She will face a rematch Dec. 6 against challenger Chris Bailey. Bernard and Bailey have enjoyed support in the past from local business leaders, though Bailey has won that support in this race. Challengers Joan Wallyn and Charles O’Brien lagged far behind.

Incumbents Vereta Lee, Tarvald Smith and Barbara Freiberg won handily their races in districts 2, 4 and 7. Lee and Smith were both opposed by business interests; Freiberg earned their support.

Turnout on Tuesday ranged from 42 percent in District 4 to 49 percent in District 1.

The East Baton Rouge Parish school system, with more than 42,000 students, is the second-largest in Louisiana. It is home to some of the highest- as well as some of the lowest-performing schools in the state.

In recent years, it has faced growing competition from charter schools and private schools that accept publicly financed vouchers. In the last 11 years, three parts of the parish — Baker, Central and Zachary — have broken away and formed independent school districts. Since 2012, some residents in the southeast part of the parish have sought to bolt as well. The effort has morphed into the effort to create a city of St. George, and, if successful, a companion school district.

To a great extent, this year’s school board elections are a replay of ones held in fall 2010.

Once again on one side are candidates supported by the Baton Rouge Area Chamber and Cajun Industries founder Lane Grigsby; they are pressing for business-backed reforms of public education, including expansion of charter schools. On the other side are candidates who are supporters of traditional public education and who oppose, to varying extents, the business-backed agenda.

In 2010, business interests spent more than $300,000 to win narrow control of the School Board. This year, they are on track to spend a similar amount of money and on are track to keep and perhaps expand that control.

Three of the five board members targeted by business interests in 2010 nevertheless managed to win re-election. The result was a board divided 6-5 on an array of issues.

From the start of this election season, the School Board was going to look different than it did in the past. The nine-member School Board that takes office Jan. 1 is two seats smaller than the current 11-member board. The board, on July 24, voted by a narrow majority and after many hours of debate to reduce its size. A subsequent challenge in state court to the last-minute redistricting was unsuccessful.

Of the six races on Tuesday’s ballot, three were won and three went to runoffs.

Three seats — districts 3, 6 and 9 — are already filled as incumbents Kenyetta Nelson-Smith, Jill Dyason and David Tatman had no opponents, thus were re-elected without opposition. Tatman had no one qualify to run against him, while Nelson-Smith and Dyason had opponents who withdrew after losing court challenges to their residency. Tatman and Dyason are supported by business leaders while Nelson-Smith is not.

The nine new districts cover more territory and each have 7,000 more residents on average than the previous districts. In terms of residents, five are majority-white and four are majority-black.