Update 9:35 p.m.: All seven of Cook County's precincts are reporting, putting Turelli's lead over Neerhof at 558 votes out of 8,954.
Neerhof's campaign manager Mick Paskiewicz told Patch he was looking into how many early and absentee votes had been cast that have not yet been counted.
When asked if they were still in the race, Paskiewicz replied "We're not out of it."
Update 9:15 p.m.: Mark Neerhof is speaking to a gathering of supporters at his election night event in Lake Forest. He's not conceding, but he is calling a win "unlikely."
The Lake Forest doctor currently trails Lauren Turelli by 548 votes.
"These results are not what we hoped," Neerhof said.
Update 9:10 p.m.: Neerhof is now losing to Turelli in both Lake and Cook Counties with all but one Cook County precinct yet to report.
Update 9 p.m.: Mark Neerhof is trailing Lauren Turelli by 281 votes with all but two precincts yet to report.
In Lake County, Turelli is up by 290 votes, with 3,228 to Neerhof's 2,938. In Cook County, with five precincts out of seven reporting, Neerhof leads with 149 votes to Turelli's 140. That gives Turelli a 281 vote leads.
Earlier: The Republican primary race for the 58th State Representative seat is a close one.
As of 8:47 p.m. Tuesday, Dr. Mark Neerhof leads in Cook County 114 votes to 113, but is trailing in Lake County to Lauren Turelli by about 300 votes out of a totaly of 6,166.
All of Lake County's precincts have reported, but Cook County is still waiting on three more.
"He's a real honest man," said Lake Forest resident Cheryl Hobart at Neerhof's election night event at Conway Farms Golf Club in Lake Forest. She's known Neerhof for 25 years and made phone calls on behalf of his campaign. "Mark is just a first class guy."
Neither Turelli nor her campaign staff returned calls to Patch about where she would be as the election results came in.
Neerhof, 52, of Lake Forest, announced his candidacy last August. This was his first run for public office. As a 20-year obstetrician in the Chicago area, he made his opposition to President Barack Obama's health care plan a major focus to his campaign.
Turelli, also a Lake Forest resident, lost to Karen May (D-Highland Park) in the general election for the same seat in 2010 with 43 percent of the vote.
A former teacher, Turelli's campaign focused on education, the state’s finances and job creation.
Keep checking back for more updates.