Cruz developed a loyal following when he won his 2012 primary battle in Texas as a little-known candidate, forcing then-Lt. Gov. David Dewhurst into a surprise runoff and ultimately defeating the establishment Republican.
In Washington, Cruz has done nothing but infuriate the Republican Party establishment
. He tried to shut down the government over Obamacare, and he angered then-House Speaker John Boehner by crossing the Capitol to fan an insurgency among radical lawmakers over budget issues. Eviscerating the Senate's courtly manners, he accused Majority Leader Mitch McConnell, a fellow Republican, of lying.
His attitude has made him toxic to his colleagues but appealed to those who feel much the same way about the GOP leadership.
But the unimpeachable anti-establishment credentials that Cruz built up in Washington, combined with his natural affinity for evangelical Christians and existing popularity among tea party Republicans, have built him a powerful political base.
Texas and Canadian roots
Before running for the Senate in 2012 -- his first campaign for public office -- Cruz was solicitor general of Texas and argued before the Supreme Court. He previously worked on the Florida recount operation for Republican George W. Bush in 2000 against Democrat Al Gore. Cruz graduated from Princeton University and Harvard Law School.
Born in Canada to a Cuban father and American mother, Cruz was a dual citizen until he renounced Canadian citizenship in 2014. He faced questions over whether he would qualify for the presidency, though law experts consider him a natural-born citizen because he was born to an American mother.
Trump has raised questions about whether the Texas senator is eligible to become president based on where he was born, however.
"He's got a problem," Trump told a New Hampshire audience on January 11. "Whether you like it or not, Ted has to figure it out."
He went on: "You can't have a nominee who's going to be subject to being thrown out as the nominee. You just can't do it. So you gotta make that decision, folks."
Cruz has brushed aside Trump's claims.
"The Internet has all sorts of fevered swamp theories
, but the facts are simple," Cruz recently told CNN's Jake Tapper on "State of the Union."
"My mom was born in Wilmington, Delaware. She was an American citizen by birth. She's been an American citizen all 81 years of her life. She's never been a citizen of any other place."
Cruz, who was the first to declare his presidential candidacy, talked about his Cuban roots to the audience at Liberty University during his kickoff speech.
"We grew up speaking Spanglish. My grandmother would be like 'Niño, throw me the remote control'," he said This is who we are as a people. We got to tell that story," Cruz said on March 23, 2015.
Cruz met his now-wife, Heidi, on the 2000 campaign trail.
"It was love at first sight," Heidi Cruz said in a January interview
with CNN's Dana Bash. "Of course you always think you know ... a first thought is what is the person, what is your sense of them. How are they reacting to you? And Ted just seemed to be interesting. He was a good-looking guy. He greeted me with a smile."
Heidi Cruz worked at the George W. Bush White House on the National Security Council, and subsequently joined Wall Street bank Goldman Sachs. She is on leave from the bank.
The Goldman Sachs connection has spurred some controversy. It was reported that Cruz failed to properly report
hundreds of thousands of dollars in loans from Goldman and Citibank for his 2012 Senate campaign. Cruz has described the incident as a paperwork error.
"These loans have been disclosed over and over and over again," Cruz told reporters
quickly after the news broke in January. "It is an inadvertent filing question. The facts of the underlying matter have been disclosed for many, many years."
The Cruz family lives in Houston with their two daughters, Caroline and Catherine.
Backing from evangelicals
Ten-thousand students from Liberty University crowded into an arena for Cruz's announcement. The venue choice at this socially conservative campus foreshadowed his aim to appeal to evangelical voters, a key constituency he has courted.
Cruz's announcement -- which came on the five-year anniversary of the passage of the Affordable Care Act, also known as Obamacare -- aimed to highlight his opposition to the law.
Cruz has fought in the Senate to repeal it, even orchestrating a 17-day government shutdown
in a failed attempt. Cruz marked the anniversary by pledging to repeal "every word" of the health care law as president.
He has also jabbed at Common Core education standards and repeated his pledge to abolish the Internal Revenue Service, instead suggesting Americans could file their taxes on a postcard.