Republican Sen. John Kuhn trailed a former top aide to Gov. Mark Sanford in one of the most hotly contested primary races for the state Senate on Tuesday.

With more than three-quarters of the vote in, challenger Chip Campsen held a narrow lead over Kuhn, who has clashed with first lady Jenny Sanford over her support for Campsen.

All told, more than a dozen Senate seats were up for grabs in the Democratic and Republican primaries.

Kuhn was one of at least three Senators facing a tough primary race as results began to come in Tuesday night. In most races, incumbents who had been challenged were on their way to victory.

But in Kuhn’s case, the balloting was tight through much of the night for the Charleston-area seat.

Campsen, the governor’s former top legislative aide, has criticized Kuhn for failing to help Sanford pass a government restructuring plan that supporters say would make the state more efficient. He has called the difference between himself and Kuhn on some issues “dramatic.”

Kuhn, elected three years ago, has denied working against the governor. But he recently got into a shouting match with the governor’s wife over her support for Campsen. Kuhn says he’s closer to the voters than Campsen, and has denied being difficult for Sanford to work with.

Charleston City Councilman Henry Fishburne, a third candidate for the Republican nomination, trailed the field Tuesday.

Kuhn said he expected to be in a June 22 runoff with Campsen.

“We knew we would be in a runoff; our polls have told us that,” Kuhn said. “But we are feeling good about the race.”

The Republican nominee faces Democrat Constance Anastopoulo in the November general election. The seat stretches from the Isle of Palms to near Kiawah Island and inland toward Summerville.

In the Pee Dee, Sen. Maggie Glover, D-Florence, narrowly led Tuesday night in her primary race against challengers Kent Williams and Tim Norwood. Glover is the state senate’s only black woman.

Also, Sen. Bill Branton, R-Dorchester, was losing in his race with Randy Scott. Sen. Yancey McGill, D-Williamsburg, won a close race with former state Rep. Ted Brown.

In other races, longtime Democratic Sen. John Drummond was easily outdistancing former Greenwood school superintendent David Henderson. Drummond, 84, is the longest-serving current member of the Senate. The district is in western South Carolina, encompassing the Greenwood area.

Democratic Sens. Robert Ford of Charleston and Ralph Anderson of Greenville were among those who won primary races handily.

In two other races of note, a handful of candidates sought to replace retiring Sens. Arthur Ravenel, R-Charleston and Bob Waldrep, R-Anderson.

In Ravenel’s district, Murrells Inlet dentist Ray Cleary was on the way to victory over retired Circuit Judge David Maring. The winner faces no Democratic opposition in November.

In Waldrep’s district, national Confederate heritage group commander Ron Wilson lost to former state Rep. Chuck Allen and pharmacist Kevin Bryant for the GOP nomination in Anderson County. Allen and Bryant are in a runoff. The winner goes against former state Sen. Mike Mullinax, who won Tuesday night’s Democratic primary.