WASHINGTON - US Senator Ted Cruz from the hardline Republican right announced Monday he will run for president, the first major candidate to officially declare a 2016 White House bid.

"I'm running for president and I hope to earn your support!" Cruz posted on Twitter, firing the starting gun on what is expected to be a crowded Republican nomination race.

The 44-year-old Tea Party favorite has been a US Senator in Texas since 2012, and is a fierce critic of US President Barack Obama's administration.

He has raised hackles in his own party in recent years when he helped push the US government into shutdown over budget fights, and for opposing Republican leaders on a series of issues.

In a 30-second video posted on Twitter Monday, Cruz said it was time to "restore" America, and called on young conservatives to support him.

"It's a time for truth, a time to rise to the challenge, just as Americans have always done," he said in the video.

"I believe in America and her people, and I believe we can stand up and restore our promise.

"It's going to take a new generation of courageous conservatives to make America great again and I'm ready to stand with you to lead the fight."

Cruz is expected to appear later Monday at the Christian Liberty University in Virginia, where he could flesh out his leadership ambitions.

He followed his Twitter video announcement with a longer one posted on YouTube, stressing his immigrant roots and his faith in God, and promising, with the help of supporters to "stand up and restore our promise, honor the constitution and re-establish our leadership in the world."

The Texas senator, who has Cuban heritage, also released a version of the video in Spanish in a bid to corner the support of Latinos - America's largest minority group.

His advisors told US media he will aim to raise between $40 million and $50 million for his campaign, and will rely on support from his ultra-conservative and libertarian Tea Party base that voted him in as senator in 2012.

Although the first to officially declare his presidential bid, other Republicans, including former Florida governor Jeb Bush, Wisconsin governor Scott Walker and Senators Rand Paul and Marco Rubio have signaled they too could join the race.

Retired neurosurgeon Ben Carson and former Arkansas governor Mike Huckabee are also potential candidates seeking the populist conservative vote.

At the Conservative Political Action Conference (CPAC) last month, Cruz told the crowd: "2016 looks like it's going to be a crowded race."

On his website, Cruz is described as "a passionate fighter for limited government, economic growth and the Constitution."

A CPAC straw poll conducted in February put Cruz in third place as the party's pick for president, behind Walker and Paul, a Kentucky senator.

Bush, the son and brother of former presidents, came in fifth.

Cruz's forthright conservatism and uncompromising positions have often earned him condemnation from leading figures within the Republican establishment.

John McCain, the 2008 Republican presidential candidate, once derided Cruz and two other Tea Party lawmakers as "wacko birds on the right."

The criticism has rarely fazed Cruz.

"I don't work for the party bosses in Washington. I work for the people of Texas. And I fight for them," Cruz said in a 2013 interview.

A Texas-raised, Harvard-educated lawyer with a Cuban father and an American mother, Cruz was born in Canada.

Although he was entitled to US citizenship at birth, his foreign birthplace could become a point of contention during his campaign for president - a job restricted to natural-born citizens.

Cruz joined George W. Bush's legal team to argue the 2000 Florida presidential recount. He later served under Bush in the Justice Department and the US Federal Trade commission.

In 2003 he returned to Texas and was appointed solicitor general, where he served for five years.

Cruz ran for Senate in 2011 with support from the Tea Party - anti-government, anti-tax, and pro-life and pro-gun conservatives who thrive in politically conservative Texas.

He defeated the establishment Republican candidate, then steamrolled his Democratic opponent in the 2012 election.

Cruz may have a Hispanic last name and enjoyed plenty of support in Hispanic-heavy Texas when he was elected, but he is a staunch opponent of immigration reform, a key issue in the Hispanic community.

He responded to Obama's executive action on immigration by urging fellow lawmakers to do all they could to block the measure, branding it "an illegal amnesty."