Jeb Bush jumped off the sidelines and into the Republican presidential race on Monday, kicking his campaign-in-waiting into gear after spending months raising money and lining up support. 

The former Florida governor formally announced his 2016 bid at a rally in Miami, vowing to use his executive experience to make Washington work again. 

"I'm a candidate for president of the United States of America," Bush said. "We will take command of our future once again in this country." 

In formally announcing his bid, Bush seeks to recapture the momentum he initially generated, only to watch several other GOP candidates seize the spotlight while he made preparations. 

No longer the unquestioned front-runner, Bush has to contend with 10 other candidates who already have declared and several more expected to enter in the coming weeks. Lately, he's been bunched at the top of national Republican polls with Wisconsin Gov. Scott Walker, who has not yet declared, and home-state rival Sen. Marco Rubio, R-Fla., who has. Yet Bush remains an undeniable force in the race and still leads the field by a slim margin, according to the RealClearPolitics average of polling.   

On Monday, Bush vowed to "take nothing and no one for granted." 

"I will run with heart. And I will run to win," he said. 

Bush cited his record as governor and vowed to take Washington "out of the business of causing problems." 

"I know we can fix this. Because I've done it," he said. 

On Monday morning, he also released a web video pitching himself as a problem-solver. 

 

His campaign logo, "Jeb! 2016," notably does not use his last name -- a factor that has been both an asset and a liability in the race. At the same time, Bush did not shy from his family name during the rally. In one memorable line, he noted that the most "improbable" things can happen, saying, take that "from a guy who met his first president on the day he was born, and his second on the day he was brought home from the hospital." 

He then introduced his mother, former first lady Barbara Bush, who was in attendance. 

The rally was held near his south Florida home at Miami Dade University, an institution selected because it serves a large and diverse student body that's symbolic of the nation he seeks to lead. The event was held in Bush's home state, but also a vital presidential swing state. 

Speaking before Bush took the stage, state Sen. Don Gaetz appeared to take a shot at the other candidate from Florida, Rubio. "Jeb Bush is the Florida Republican who can win," he said. 

Underscoring Bush's outreach to Latino voters, several speakers at the kick-off addressed the crowd in Spanish, including Bush, who speaks the language fluently. 

Bush joins the crowded Republican campaign in some ways in a commanding position. The brother of one president and son of another, Bush has likely raised a record-breaking amount of money to support his candidacy and conceived of a new approach on how to structure his campaign, both aimed at allowing him to make a deep run into the GOP primaries. 

But on other measures, early public opinion polls among them, he has yet to break out. While unquestionably one of the top-tier candidates in the GOP race, he is also only one of several in a capable Republican field that does not have a true front-runner. 

In the past six months, Bush has made clear he will remain committed to his core beliefs in the campaign to come -- even if his positions on immigration and education standards are deeply unpopular among the conservative base of the party that plays an outsized role in the GOP primaries. 

"I'm not going to change who I am," Bush said as he wrapped up a week-long European trip this weekend. "I respect people who may not agree with me, but I'm not going to change my views because today someone has a view that's different." 

Bush is one of 11 major Republicans in the hunt for the nomination. But few among them entered the race with such high expectations of success as did Bush. Those expectations have seemed a burden at times. 

Take, for example, the question of whether Bush will report raising $100 million for his campaign in the first six months of the year. Lost amid the "will he or won't he" is that Bush probably will have raised more in six months than former presidential nominee Mitt Romney raised in the first year before the 2012 election. 

After touring four early-voting states, Bush quickly launches a private fundraising tour with stops in at least 11 cities before the end of the month. Two events alone -- a reception at Union Station in Washington on Friday and a breakfast the following week on Seventh Avenue in New York -- will account for almost $2 million in new campaign cash, according to invitations that list more than 75 donors committed to raising big money. 

The Associated Press contributed to this report.