Republican White House hopeful Mitt Romney tried to boost support on Florida's "Space Coast" Friday ahead of next week's key primary, promising business would play a bigger role in future missions.

Romney criticized US President Barack Obama, who during his first term in office ended the space shuttle program, for lacking a clear vision for the future of space exploration -- a failing which he said had cost jobs.

"It's time to have a mission for the space program of the United States of America!" he told supporters at an aerospace factory in Cape Canaveral, eastern Florida, promising a less top-down approach that includes the private sector.

"In the politics of the past, to get your vote on the Space Coast, I would come over here and promise hundreds of billions of dollars... I'm not going to do that," he said, laying out his vision of missions based on military, medical and other needs.

"There is another mission to our mission in space," he said, "that is commercial. Technology and science lead to the development of products that improve our economy."

Romney took to the stump at Astrotech, a commercial aerospace company based in Cape Canaveral, that was subtly offered up as the archetype of Romney's vision for space travel.

The firm, listed on the NASDAQ stock exchange, adapts space technology for earth use and designs space hardware, as well as working as a contractor for NASA and other government agencies.

The firm's location, Cape Canaveral, is host to NASA's Kennedy Space Center, the spiritual home of the US space program.

It was from this city in 1969 that the Apollo 11 space shuttle slipped the surly bonds of Earth and delivered a man to the Moon for the first time in human history.

Since then the city's history, like that of most of Florida, has been checkered by economic boom and bust.

Today, it is mostly bust. Residents have been hit with a potent cocktail of high unemployment, the explosion of the housing bubble and the end of the space shuttle program, which drew business and tourists in their droves.

"We have been hit by the recession, but with the end of the shuttle it is worse and then of course a lot of houses went under," said a waitress at a local restaurant who identified herself only as Kim.

"We still get some people coming because they still launch rockets and stuff, which some people like, but you should have seen this place during the last three shuttle launches -- it was crazy."

Romney's speech was just one in a series given across Florida on Friday, as he criss-crossed the state from north to south and back to north again in a frantic final push for votes.

Republicans will go to the polls on Tuesday to decide who they want to face Obama, the Democratic incumbent, in November's presidential elections.

After votes in three different states resulted in three different winners -- former senator Rick Santorum in Iowa, Romney in New Hampshire, and former House speaker Newt Gingrich in South Carolina -- the primary could prove decisive in shaping the race.

It is in Florida that Romney, long the assumed nominee, has faced the stiffest in a series of challenges from the right flank of the Republican Party -- the latest being from Gingrich.

For Gingrich, Florida is a virtual must win if he hopes to keeps his presidential dreams alive.

According to the Real Clear Politics' poll average, Romney leads the state with 39 percent against Gingrich's 32 percent. Santorum and Texas congressman Ron Paul trail the field with 11 percent and 10 percent, respectively.

After a feisty debate on Thursday night, which saw flashes of steel from Romney that have seldom been seen on the trail so far, the former Massachusetts governor appeared buoyant Friday.

"How about that debate last night," he began the rally in Cape Canaveral to rambunctious applause. "Battling was fun and battling was won, I can tell you."