Jeb Bush
Republican U.S. presidential candidate and former Florida Governor Jeb Bush formally announces his campaign for the 2016 Republican presidential nomination during a kickoff rally in Miami, Florida June 15, 2015.Reuters

Jeb Bush cast himself as a more moderate type of Republican while still holding on to his conservative principles as he began his US presidential bid with an eye on the Hispanic vote which has eluded the party for years.

The former Florida governor announced his campaign for the Republican nomination to run in the November 2016 election at a multicultural college in Miami where he promised to pass meaningful immigration reform, spoke fluent Spanish and reminded voters he married a Mexican.

It was part of an effort by Bush, 62, to strike a different tone in a crowded field of 10 other Republicans and at the same time also showing he was keen to move out of the shadow of his father and brother and their White House legacies.

Even though the Bush family has a long history at the pinnacle of Washington government and politics, Bush portrayed himself as an outsider. He vowed to reform Washington, but Bush is only the latest candidate in the field to do so.

"We don't need another president who merely holds the top spot among the pampered elites of Washington. We need a president willing to challenge and disrupt the whole culture in our nation's capital," Bush, who was governor of Florida from 1999 to 2007, told supporters at Miami Dade College.

His speech was mostly the standard Republican fare of attacks on big government and promises to protect free enterprise and strengthen America's role in the world.

But the tone of the campaign launch showed he seeks to use his links to Latino culture to give himself a lift over his Republican rivals, even if two of them - senators Marco Rubio and Ted Cruz - have stronger Hispanic credentials than Bush does.

Bush was preceded on stage by the Chirino Sisters, a Miami singing trio who sang a classic Cuban song, and an African-American preacher.

"As a candidate, I intend to let everyone hear my message, including the many who can express their love of country in a different language," Bush said, before switching to Spanish and calling on Latinos to "help us have a campaign that welcomes you."

Latinos will make up more than 10 per cent of the electorate in 2016 and are important in swing states such as Nevada, Florida and Colorado.

Failure to win the Latino vote plagued Republican presidential candidate Mitt Romney who was supported by only 27 per cent of Hispanic voters in 2012 after opposing comprehensive immigration reform and making comments seen as anti-immigrant.

Senator John McCain of Arizona won 31 per cent among Hispanics in 2008, down from a stronger performance by Bush's brother President George W. Bush who was backed by 44 per cent of Latino voters in 2004.

LATINO VOTERS

"I think Republicans have got to try something. It's pretty hard for them to win the White House if current Hispanic voting trends continue. (Bush) has some unique abilities to appeal to those voters and he's going to maximise them," said David Yepsen, director of the Paul Simon Public Policy Institute at Southern Illinois University.

Bush's speech on Monday was briefly interrupted by pro-immigration reform protesters.

He quickly responded: "By the way. Just so that our friends know. The next president will pass meaningful immigration reform so that that will be solved not by executive order," Bush said, in reference to President Barack Obama's use of presidential powers to ease immigration restrictions.

Bush held an early lead in opinion polls of Republican voters when he first began talking about a White House run six months ago, but that has now dissipated. He is essentially tied for the lead with a host of challengers.

He was joined on Monday by his mother Barbara Bush, 90, at the event. Former presidents George H.W. Bush, his father, and George W. Bush, his brother, did not attend.

Bush reminded voters that his wife Columba was a Mexican he met on a visit south of the Rio Grande more than 40 years ago.

"In 1971, 8 years before then-candidate Ronald Reagan said that we should stop thinking of our neighbors as foreigners, I was ahead of my time in cross-border outreach," Bush said.

Both previous Bush presidents left office with low approval ratings. The legacy of Jeb's brother is particularly difficult because he ordered the 2003 invasion of Iraq and the financial crisis that erupted toward the end of his time in office.

Distancing himself from the pair, without being disloyal to his family, will be tricky for the younger Bush. His campaign logo "Jeb!" avoids using the family surname.

"I think the biggest hurdle is he is going to have to sell himself as his own person, not his brother and not his father," said Fran Hancock, 64, a supporter who was at Monday's event.

Bush criticised former secretary of state Hillary Clinton, the front-runner for the Democratic nomination in 2016.

"With their phone-it-in foreign policy, the Obama-Clinton-Kerry team is leaving a legacy of crises uncontained, violence unopposed, enemies unnamed, friends undefended, and alliances unraveling," he said.

Democrats made sure to remind voters of the George W. Bush's record.

"We already know what to expect from a Bush presidency, because we've seen it before. Jeb Bush supported his brother's disastrous economic and foreign policies that made us weaker at home and abroad," said Rep. Debbie Wasserman Schultz, head of the Democratic National Committee.