COLUMBIA - Voters on Tuesday will pick their parties' choice to be South Carolina's education superintendent, while Republicans will also pick their lieutenant governor nominee.

Turnout for the primary runoffs is expected to be light. Just 16 percent of the state's registered voters cast ballots in the June 10 primary, when contests included five statewide races and both U.S. Senate seats.

Two weeks later, the Republican ballot features two statewide races: Henry McMaster versus Mike Campbell for lieutenant governor, and Molly Spearman versus Sally Atwater for superintendent. The Democratic ballot pits Sheila Gallagher against Tom Thompson for superintendent.

Democrats in Chesterfield, Darlington and Marlboro counties will also choose who they want to replace state Rep. Elizabeth Munnerlyn, D-Bennettsville, who is not seeking a third term. Voters in 11 of the state's 46 counties will also have runoff choices in local races.

In Berkeley County, Republican voters will choose between incumbent Supervisor Dan Davis and challenger Bill Peagler, the mayor of Moncks Corner, as well as between incumbent District 6 Councilman Jack Schurlknight and challenger James Law, state Department of Transportation spokesman. Davis and Schurlknight were targeted as "Republicans in Name Only" by a local conservative grassroots group; there is no Democratic candidate in either race.

The polls open from 7 a.m. to 7 p.m. Tuesday. Registered voters who skipped the primary can still cast ballots in the runoff.

What's not allowed is party switching between the two contests. People who voted June 10 must vote in the same party's runoff. Voters don't register by party in South Carolina. But those who voted on the GOP ballot for the primary, for example, can't vote in the Democratic runoff, and vice-versa.

A runoff is required when no candidate surpasses 50 percent of the vote.

McMaster, 67, took 44 percent of the votes in the four-way GOP primary for the state's No. 2 post. Campbell, 45, received 24 percent.

Both have brought in potential 2016 presidential hopefuls to boost their candidacy in the last few days. Former Arkansas Gov. Mike Huckabee campaigned across South Carolina on Saturday with Campbell, son of the late Gov. Carroll Campbell and state chairman of Huckabee's 2008 presidential bid. Former Pennsylvania Sen. Rick Santorum campaigned Monday in Greenville and Spartanburg counties with McMaster, South Carolina's former attorney general and state GOP chairman.

The votes for second and third place were so close, an automatic recount was expected. Pat McKinney, a retired Kiawah Island developer in his first run for office, received about 1,250 more votes than Campbell, but he decided to bow out, putting Campbell in the runoff.

The winner of the runoff will face Democratic state Rep. Bakari Sellers in November. Sellers, 29, is not seeking a fifth term representing Bamberg County and portions of Barnwell and Colleton counties.

This year is the last time voters will choose the lieutenant governor. Starting in 2018, gubernatorial nominees will pick their running mates.

In the GOP superintendent's race, Spearman finished first among eight candidates, but only 1,408 votes ahead of Atwater. Each received roughly 22 percent of the vote.

Both say they want to implement Gov. Nikki Haley's education improvement plan, which focuses on poor, rural students. Atwater, widow of GOP strategist Lee Atwater, said she got excited after reading the plan on her district's website. Spearman, director of the state Association of School Administrators, was among the educators Haley met with to develop the budgetary suggestions she released in January. Both attended Haley's celebration earlier this month of her plan's passage in the state budget.

On the Democratic side for superintendent, Gallagher took 36 percent of the vote in the four-way primary, while Thompson received 26 percent.

Gallagher, former president of the South Carolina Education Association, has attracted attention by advocating legalizing and taxing marijuana to raise money for schools. Thompson, former dean of graduate studies at South Carolina State University, said it is absurd to link buying marijuana to quality education.

Editor's note: A previous version of this story incorrectly stated where Bill Peagler is mayor. The error has been fixed.