MASON CITY, Iowa — Republican presidential candidate Newt Gingrich said on Wednesday his failure to meet the requirements to take part in Virginia's presidential nominating contest resulted from fraud by a worker hired by his campaign.

Gingrich, who lives in Virginia, scrambled to submit the petitions necessary to get on the ballot on time, but the state party said on Saturday a review process showed he did not have the required 10,000 verifiable signatures.

Gingrich's campaign hired workers to gather those signatures, and the former speaker of the House of Representatives said at a campaign stop that one of those workers had committed fraud.

"We hired somebody who turned in false signatures. We turned in 11,100 - we needed 10,000 - 1,500 of them were by one guy who frankly committed fraud," Gingrich said, according to CNN.

Gingrich had been leading his Republican rivals in the state. Former Massachusetts Governor Mitt Romney and Texas Congressman Ron Paul were the only candidates from the field of top Republican candidates to qualify to be on Virginia's ballot.

Republican presidential candidate Rick Perry also failed to qualify in Virginia because he lacked the 10,000 verifiable signatures.

On Tuesday he filed a federal lawsuit challenging Virginia's qualification process on constitutional grounds. Perry said it restricts the access of the state's voters to the candidates of their choosing.