The number of legal immigrants seeking to become United States citizens is surging, officials say, prompted by imminent increases in fees to process naturalization applications, citizenship drives across the country and new feelings of insecurity among immigrants.

The citizenship campaigns have tapped into the uneasiness that legal immigrants, especially Hispanics, say is a result of months of debate over an immigration bill that failed last week in the Senate. Although illegal immigrants were the center of attention in the debate, it prompted many legal immigrants who have put down roots here to seek the security of citizenship, as well as its voting power, immigrants’ advocates said.

The numbers of new naturalized citizens have steadily grown, to 702,589 last year from 463,204 in 2003. A big jump occurred this year, with the number of applications increasing every month, to 115,175 in May compared with 65,782 last December.

More than 4,000 new Americans were sworn in yesterday in tradition-steeped — and some not so traditional — Fourth of July ceremonies. About 1,000 people from 75 countries took their oaths together under the turrets of Cinderella’s Castle at Walt Disney World in Lake Buena Vista, Fla., as Gloria Estefan sang “The Star-Spangled Banner.”