PHOENIX — With nearly 16,000 independents in Pima County, and another 50,000 in Maricopa County, having already requested early ballots, candidates in close primary races who ignore that element put themselves at risk.

Maricopa County Recorder Helen Purcell said requests in her county are already well ahead of the combined 43,000 independents who voted in the primaries two years ago, both early and at the polls.

Chris Roads, the chief deputy Pima County recorder, said he cannot directly compare this year’s independent ballot requests to 2012 because of a computer system change.

But Roads said the number of requests his office has seen suggests a strong interest by Pima independents in influencing the partisan primaries.

And Purcell said if those voters went to the trouble of requesting a ballot, she expects at least 90 percent of them will be returned.

A new statewide poll by the Behavior Research Center supports the notion of a strong independent turnout for the Democratic and Republican primaries.

The poll shows a third of all independents questioned say they intend to participate in the Aug. 26 primary, with another quarter saying they’re not sure yet.

Independents can vote in the primary of their choice. They just have to notify their county election officials which party’s primary they want to vote in.

If they turn out in force, they would have significant impact.

The most recent statewide voter registration figures show nearly 34.9 percent of the 3.25 million people eligible to vote are affiliated with none of the four recognized political parties. Republicans make up less than 34.8 percent of the electorate, with Democrats at about 29.5 percent.

Jim Haynes, president of Behavior Research Center, said the implications go beyond the sheer numbers.

He said those who have opted to register as independents and moved away from either major party are likely more moderate than those he calls the “true believers” in each camp — the ones who, until now, have controlled the nomination process.

And that, Haynes said, could provide a boost to candidates from both parties who appeal more to the political center.

Haynes conceded that what people tell pollsters now does not necessarily translate to what they will do.

But Purcell said she has reason to believe independents will be turning out in force.

“They have made a special effort,” she said, versus those who are on the permanent early voting list and automatically get a ballot in the mail. “To me, they have already invested in this election,” Purcell said.

“It’s going to make a tremendous difference,” she said of a high turnout by independents in partisan primaries. “People better be appealing to those independent voters if they want to go anywhere.”

Pollster Earl de Berge said the impact of independents could be enhanced if significant numbers of Republicans avoid certain races or do not turn out at all. He said, for example, that the number of Republicans who say they are undecided among the six candidates for governor is in the 50 percent range, something he said is quite unusual given that early voting starts in a week.

The live telephone survey of 703 adult heads of household was conducted earlier this month. The margin of error among those who identified themselves as independent is 6.5 percentage points.