The primary runoff race for state labor commissioner last week, which may end up costing as much as $4 million, is a case in point why legislators should seriously consider an instant-runoff election system.

We're glad that Democrat Mary Fant Donnan of Winston-Salem won the runoff and the right to challenge Labor Commissioner Cherie Berry, a Republican, in November.

But the costs of these runoffs are out of control, especially given their pitifully low turnouts. Barely 75,000 votes were cast in last week's election, according to Bob Hall of Democracy North Carolina, and the runoff cost more than $50 per vote for election officials to administer. Forsyth County came out a little better -- a cost of about $36 per vote for the 2,169 votes cast, according to Rob Coffman, the county elections director. But in some counties, Hall said, "the cost for the local board of elections easily exceeded $70 per vote."

Local taxpayers foot the bill instead of the state, Hall said, and that may be one reason why state legislators have been slow to deal with this costly problem. Voters should urge lawmakers to move faster on this -- and seriously consider instant runoff.

Voters participating in instant runoffs rank their choices for office in multicandidate races. If the election produces no clear winner, the top two vote getters enter a virtual runoff. "It's essentially looking at the voter's preference of the two remaining candidates," Hall said. "You mark who you really want to win as your first choice, and then you make a backup choice. If your first choice is eliminated, that's the only time they look at your backup choice."

The 2007 General Assembly did approve two pilot projects for instant runoffs, in Cary and Hendersonsville. Those projects generally went well. The process was easy and satisfying, voters in Cary told an independent researcher.

Certainly, more education is needed about instant runoffs. Voters can learn more about it at Democracy North Carolina's Web site, www.democracy-nc.org.

Elections officials still have a few kinks to work out of the system, but it appears to be a promising option for replacing costly runoffs. Besides the cost savings, the system should enhance the democratic process. That's because most voters who turn out for a primary or general election won't return to vote in a runoff.

That certainly happened in the runoff in the labor commissioner race, as advocates Elena Everett and Lynice Williams predicted in a column published in The News & Observer of Raleigh before that runoff: "On May 6, 1.2 million people voted for the preferred candidate in the labor commissioner race. If past trends hold, the final outcome will be determined by fewer than 100,000 voters."

Past trends held. And local taxpayers were once again left holding the bag. A serious consideration of the instant-runoff voting system in this state is long overdue.