"Surpassing the goal of one million applications is a tremendous achievement," said Arturo Vargas, head of the National Association of Latino Elected and Appointed Officials (NALEO) on Monday.

Immigrants from Latin America represent the biggest ethnic minority in the United States -- some 45 million people. They could wield decisive weight in November's election, especially in largely Hispanic states such as Florida, Nevada, New Mexico and Colorado.

NALEO is one of several groups running a campaign to mobilize the Hispanic vote with the early presidential nominating contests underway and immigration a hot topic.

The US Citizenship and Immigration Services received 1.029 million applications for citizenship from immigrants between January and October 2007, the organizations say, citing official figures.

The figure -- a 10-year record, and twice the number for the previous year -- overwhelmed the offices processing the claims, causing a backlog.

The USCIS said in November it could not process all the applications at the normal speed.

"Our campaign is committed to building the support we need to clear this backlog," said Cecilia Munoz, vice-president of the biggest Hispanic group, the National Council of La Raza.