Democrats are crying foul after at least 13 candidates registered last month to run as members of the Green Party, putting them in position to act as spoilers in several key races.

The Arizona Democratic Party believes that Republicans are behind a conspiracy that violates state and federal law. They're seeking a formal investigation into the unusual number of Green Party write-in candidates, most of them former Republicans, who threaten to derail Democrats in at least four swing legislative districts and races for Corporation Commission, secretary of state and treasurer.

More than 800 votes behind with few left to count, Andy Thomas was expected to concede the GOP nomination for Arizona attorney general Monday to Tom Horne.

Horne claimed victory Monday, saying that once Saturday's votes were tallied there was no way Thomas could catch him.

"It’s become a mathematically impossibility," Horne said.