A nationwide door-to-door drive to register 1 million new Hispanic voters was launched here today with predictions that a surge of Hispanic electoral power in key states could prove decisive in the 1984 presidential campaign.

The effort is the most ambitious undertaken to translate rapid Hispanic population growth into political muscle at the ballot New Mexico Gov. Toney Anaya, a Democrat elected last year, said the goal is to increase Hispanic voter registration from 3.4 million in 1980 to 4.4 million or more by election day 1984. Anaya said there are an estimated 5.9 million Hispanic citizens of voting age.

"The bottom line is this--so many Hispanics are still not registered to vote that there is vast potential for a registration drive of a magnitude never before seen in America," he said.

The voter registration s being modeled on highly successful similar efforts in Texas and elsewhere in the Southwest by the Southwest Voter Registration Education Project. But the nationwide scope of the 1984 effort represents a major departure from the town-by-town efforts that have been tried previously to bring Hispanic voters to the polls.

Hispanics are the nation's second largest and fastest growing minority. Political strategists of both parties have recognized their potential as a voting block in the states that are crucial to a presidential victory: Texas, Florida anifornia.

In 1980, President Reagan won between 25 and 30 percent of the traditionally Democratic Hispanic vote, the largest percentage of any GOP presidential nominee in recent years.

Looking toward next year, the White House is hoping to use Reagan's appeal to Hispanics to buffer the growing turnout of black voters who have overwhelmingly supported Democratic candidates. At the same time, Democrats have set a goal of bringing Hispanic voters who defected to Reagan in 1980 back into their party.

Reagan this Friday begins several weeks of political emphasis on Hispanic issues with campaign stops across the Southwest and in Florida. Democratic National Chairman Charles T. Manatt and San Antonio Mayor Henry Cisneros today launched a preemptive rhetorical attack on Reagan.

"Hungry Hispanic children can't eat White House press releases and the 30 percent of unemployed Hispanic teen-agers can't get jobs from presidential media events," Manatt charged at a newsrence. "If President Reagan hopes to gain the attention of the Hispanic community, he is going to have to do more than serve tacos and enchiladas to Queen Elizabeth."

William C. Velasquez, executive directorn-Partisan Voter Registration Project, told the opening of a two-day session devoted to voter registration that Hispanic voters are "broadening" their horizons.

He said polls conducted for the group show that Hispanic voters have focused increasingly in the last two years on unemployment as a major concern. Previously, Velasquez said, such local issues as paved streets and schools had dominated the Hispanic political agenda.