Texas senator Ted Cruz, one of the Republican Party's most conservative members, has launched his US presidential campaign for 2016.
Making his announcement at a crammed auditorium in Virginia's Liberty University, Mr Cruz became the first to declare in what is expected to be a crowded field of White House hopefuls.
The 44-year-old touted his family's story as the embodiment of the American dream of overcoming adversity to reach success.
He is the child of an American mother and a father who fled Cuba in 1957. When Mr Cruz was three years old, his father left him and his mother in Canada, where he was born.
His father, now an evangelical preacher, went back to the United States where he eventually found a deep Christian faith, returned to his wife and child and brought them to the US.
Elected to the US senate in 2012, Mr Cruz quickly established himself as an uncompromising conservative willing to take on Democrats and fellow Republicans alike.
At times he has been scorned at times by leading members of his own party, with fellow senator and former presidential candidate John McCain once labelling him a "wacko bird".
Mr Cruz's popularity within the right-wing base could help in the primary, a state-by-state process dominated by the most conservative Republican voters.
But his tense relationship with the Republican Party establishment complicates his path to the nomination. And if he makes it to the general election, he would have a hard time winning over moderates and independents.
In his speech, the Harvard Law School graduate spoke of the promise of America, saying, "we demand our liberty," and laid out positions antithetical to most Democrats, including the repeal of president Barack Obama's overhaul of the nation's health care system.
Mr Cruz will not be the only official 2016 candidate for long.
Several other Republicans are expected to enter the race in the coming weeks, including former Florida Governors Jeb Bush, Wisconsin Governor Scott Walker and two Senate colleagues, Kentucky's Rand Paul and Florida's Marco Rubio.
None are considered heavy favourites, though Mr Bush, the son and brother of two former presidents, had been getting the most attention in recent weeks as he takes aggressive steps toward launching his candidacy.
Whoever wins the Republican nomination would likely face former secretary of state Hillary Clinton, the front-runner for the Democratic nod who is expected to soon launch her campaign.
Mr Cruz won praise from ultraconservative tea party activists in 2013 for leading a 16-day government shutdown in an unsuccessful drive to repeal the health law, a key achievement of the Obama presidency.
"Imagine in 2017 a new president signing a law the repeals every word of Obamacare," Mr Cruz said to a cheering crowd.
He also called for the abolition of the tax collecting Internal Revenue Service, a flat tax, making abortion illegal, gun rights, and a host of other issues that put him deep in the conservative wing of the Republican party and its small-government, low-tax tea party wing.
He drew especially loud applause when he was critical of Mr Obama's difficult relations with Israeli prime minister Benjamin Netanyahu.
On foreign policy, Mr Cruz was among 47 Republican senators who signed a letter to Iran's supreme leader warning that any nuclear deal that is struck with the Obama administration and five other world powers could become null and void after the 2016 election when the current president leaves the White House.
He also is opposed to Mr Obama's executive action to ease deportations of millions of immigrants in the country illegally and to the White House opening to communist Cuba, his father's homeland.
Mr Cruz announced his candidacy on Twitter just after midnight, several hours before the official launch at Liberty University, the biggest US Christian college, which was founded by the late Rev Jerry Falwell.
The setting indicates Mr Cruz plans an aggressive courtship of cultural conservatives and young voters.