Turnout in Tuesday’s primary election was low.

Secretary of State Michael Mauro has reviewed preliminary voting data. "Based on registered Democrats, that would be about 12 (to) 13 percent and on the Republican side it would 11.5 (or) 12 percent," Mauro says.

Several races were decided by slim margins. There were fewer than 150 votes separating two of the Republican candidates seeking the G.O.P.’s U.S. Senate nomination. Mauro says those kind of tight races illustrate the power of a single vote. "That’s why it’s important that people participate in the process because it does make a difference and it’s going to have a definite determination on who the winners are," Mauro says.

Mauro hopes to have data by Thursday showing how many Iowans registered to vote on primary day. A new law which took effect Tuesday allows Iowans to register to vote at their polling place the day of the election.