Beto O'Rourke announced Friday he is dropping his presidential bid after his campaign spiraled into a free fall despite his shooting out of the starting gate.

'Our campaign has always been about seeing clearly, speaking honestly, and acting decisively. In that spirit: I am announcing that my service to the country will not be as a candidate or as the nominee,' he wrote on Twitter.

Donald Trump promptly weighed in on the news, lobby a mocking tweet at the former Texas congressman from Air Force One.

O'Rourke shot to Democratic stardom with his failed bid to take down Texas Senator Ted Cruz in 2018.

He began his presidential campaign like a rock star – with a cover on Vanity Fair and a presumed front-runner status.

Beto addressed supporters Friday after dropping out of the presidential race following a slump in polls and fundraising struggles

Instant reaction: Donald Trump tweeted his mocking farewell from Air Force One

'I want to be in it. Man, I'm just born to be in it,' he told the magazine in March.

But his campaign went down hill from there, including struggling with fundraising and dropping to 1 per cent in the polls.

He was not on track to make the November and December Democratic primary debates, which had tougher qualifications than the previous ones, in which he was on the stage every time.

O'Rourke also indicated his campaign was struggling to stay afloat financially. He only raised $4.5 million in the July, August and September.

Beto addressed volunteers in Iowa to tell them that he was dropping out of the 2020 presidential race

Over and out: Beto O'Rourke (pictured on Friday) quit as his campaign bled cash and his poll support hit just 1 per cent

Beto hugs upset supporters after dropping out of the race for the 2020 Democratic nomination

The 47-year-old vowed to support the eventual nominee and work to defeat Donald Trump next year. There are now 18 Democrats left in the campaign.

His own future is less clear. Texas has a Senate election in 2020 with Republican John Cornyn seen as a potential Democratic target as Texas' demographics shift in the party's favor. There is a December 9 filing deadline for the party primary.

Democrats had already been pressing him to drop out and run for senate, which John Hickenlooper, another 2020 hopeful, has done in Colorado.

His staff told the New York Times he had 'no plans' to enter the race - which hardly ruled it out, and his own statement did not address his next steps.

As O'Rourke announced his decision to exit the race on social media and in an email to supporters, his volunteers in Iowa were being told in person about his decision

Beto told supporters: 'My service to the country will not be as a candidate or as the nominee'

'Though it is difficult to accept, it is clear to me now that this campaign does not have the means to move forward successfully,' O'Rourke said in a lengthy farewell self-published on Medium.

'My service to the country will not be as a candidate or as the nominee.

'Acknowledging this now is in the best interests of those in the campaign; it is in the best interests of this party as we seek to unify around a nominee; and it is in the best interests of the country,' he wrote in an email to supporters.

He vowed to support the eventual nominee and work to defeat Donald Trump next year.

Democrats had already been pressing O'Rourke to drop out of the presidential race and run for senate instead

Campaign workers remove Beto For America signs after learning he is dropping out of the presidential race

'We will work to ensure that the Democratic nominee is successful in defeating Donald Trump in 2020. I can tell you firsthand from having the chance to know the candidates, we will be well served by any one of them, and I'm going to be proud to support whoever she or he is,' he wrote.

O'Rourke's first appearances to voters on the national stage were filled with apologies.

He spent his first days on the campaign trail in Iowa apologizing for what he called his 'white male privilege' after joking his wife has been raising their three children 'sometimes with my help' and for having her set silently beside him in the video where he announced his presidential bid.

And he apologized for the quote he gave Vanity Fair about the presidential race.

Remember when? Beto O'Rourke entered the race like a rock star with a cover of Vanity Fair - but went down to 1 per cent in the polls and was running rapidly out of cash

He came into the presidential race with an aura of inevitability – even Oprah Winfrey gushed over him – that he could not live up to in the fishbowl that is the presidential field.

As O'Rourke announced his decision to exit the race on social media and in an email to supporters, his volunteers in Iowa were being told in person about his decision.

The faithful were out for the state party's Liberty and Justice Celebration – a mandatory stop for a presidential candidate.

O'Rourke was scheduled to be there.

In the last few months he struggled to find his footing in the field of big-name candidates.

Last outing: O'Rourke had not qualified for the next Democratic debates this month and next after appearing on each stage so far, including October's 12-candidate debate at Otterbein University in Westerville, Ohio

At September's Democratic primary debate, he vowed to go after assault weapons, tackling an issue that hit home for him after a mass shooting at a Wal-Mart in his native El Paso in August killed 22 people, with the shooter alleged to have targeted people for being Hispanic.

'Hell, yes, we're going to take your AR-15, your AK-47. We're not going to allow it to be used against a fellow American anymore,' he said. He had stayed in El Paso in the wake of the shooting and condemned Trump forcefully.

His campaign sold t-shirts around the slogan and blasted emails to supporters to try and fundraise off it.

But O'Rourke continued to slip into candidate obscurity while the previously-unknown Pete Buttigieg shot to national fame – bringing in the party's big-dollar donors and scoring policy points in debates.

Unclear is the affect his exit will have on the presidential race. O'Rourke never caught fire with any niche group of Democratic voters – liberals, moderates, LGBTQ, or minorities.

El Paso anger: Beto O'Rourke stayed in his home town after the Wal-Mart massacre when 22 people were killed in an attack allegedly targeting people for being Hispanic.

Family: O'Rourke had launched his campaign in El Paso with his wife Amy and (from left) son Ulysses, daughter Molly and younger son Henry

His campaign outspent what it brought in, perhaps overly confident in its abilities after O'Rourke's Texas Senate bid raised a record $80 million.

His presidential campaign brought in $17 million and had $3.2 million cash on hand in its last FEC report – not enough to see him to the Iowa caucus that are less than 100 days away.

O'Rourke is personally a multi-millionaire with a father-in-law worth an estimated $500 million who had previously helped his political funding.

His own father, who died in 2001 aged 58, was a businessman and politician who switched sides from Republican to Democrat. His mother owned a high-end furniture store and now owns other property in El Paso.

O'Rouke had an elite upbringing, with his maternal grandmother marrying John F Kennedy's former secretary of the Navy in 1980, after O'Rourke was born.

As a teenager he said he was unpopular at school and joined a computer hacking group called the Cult of the Dead Cow, writing obscene poetry as part of their activities.

O'Rourke left the border town of El Paso where his family have lived for three generations to attend boarding school at Woodberry Forest school in Virginia.

He graduated from Columbia University in New York, and lived in the city for a time, working as a male nanny and trying for a career in punk music.

He admitted benefiting from 'white privilege' having been arrested for a DWI in 1998 and faced claims he had tried to run for the scene; he was also arrested for burglary in 1998.

He has three children - sons Ulysses and Henry and daughter Molly - with his wife Amy and the couple live in the El Paso house where Pancho Villa and General Hugh Scott are reputed to have met in 1915.