Two sources within the campaign tell ABC News the decision appears to be immediate.
To our 240,000 donors, our 77,000 volunteers, and everyone across the country who believed --— Team Beto (@TeamBeto) November 1, 2019
We’re proud of you, Team Beto. Keep fighting the good fight. pic.twitter.com/PdlgTjbsI1
The Democrat announced his candidacy in March, prompting media attention and polling numbers that put him among the then-front-runners and leading to an impressive first-day fundraising haul of $6.1 million.
But O'Rourke's stock steadily declined in the following months, with lackluster debate performances, a steep drop in fundraising and a plunge in the polls -- registering no more than 3% or 4% in some national and state polls. He eventually failed to secure two additional polls to qualify for the November debate, which will be hosted in Georgia by MSNBC and The Washington Post.
Our campaign has always been about seeing clearly, speaking honestly, and acting decisively.— Beto O'Rourke (@BetoORourke) November 1, 2019
In that spirit: I am announcing that my service to the country will not be as a candidate or as the nominee. https://t.co/8jrBPGuX4t
O'Rourke announced his White House bid just months after losing a closely watched 2018 midterm race in which he challenged Republican stalwart Sen. Ted Cruz, losing by just 3 percentage points. It was the closest race Texas had seen in recent decades. O'Rourke raised a record $38 million in one quarter of 2018, three times Cruz's totals for the same period and the most raised in a U.S. Senate race in history.
Finding viral and documentary fame, O'Rourke traveled to all of Texas' 254 counties, including ones not visited by Democrats in years. It was a strategy he later applied to his presidential bid following a racially motivated mass shooting in his hometown of El Paso, Texas, that claimed the lives of 22 people.
The decision to abandon the presidential campaign comes after O'Rourke renewed efforts to gain momentum in the polls.
Central to O'Rourke's strategy was a bid to win Texas in the primary. Two days before the Houston Democratic debate on Sept. 12, the campaign announced it had hired Delilah Agho-Otoghile to oversee its Texas leadership team.
Agho-Otoghile most recently served as field director for Stacey Abrams' 2018 campaign for governor in Georgia, a race that was narrowly lost to Gov. Brian Kemp.
O'Rourke was able to capture accolades from the Democratic frontrunners on the debate state in Houston for his response to the El Paso mass shooting.
He captured attention when he went after weapons "designed to kill people on a battlefield" in that debate - saying, "Hell yes, we are going to take your AR-15," -but was unable to convert that moment into a bounce in the polls.
Friday afternoon, O'Rourke released this statement on his Twitter account:
Our campaign has been about seeing clearly, speaking honestly and acting decisively in the best interests of America.
Though it is difficult to accept, it is clear to me now that this campaign does not have the means to move forward successfully. 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.
I decided to run for President because I believed that I could help bring a divided country together in common cause to confront the greatest set of challenges we've ever faced. I also knew that the most fundamental of them is fear - the fear that Donald Trump wants us to feel about one another; the very real fear that too many in this country live under; and the fear we sometimes feel when it comes to doing the right thing, especially when it runs counter to what is politically convenient or popular.
I knew, and I still know, that we can reject and overcome these fears and choose to instead be defined by our ambitions and our ability to achieve them.
I knew that we would have to be unafraid in how we ran the campaign. We'd have to run with nothing to lose. And I knew that our success would depend not on PACs or corporations but upon the grassroots volunteers and supporters from everywhere, especially from those places that had been overlooked or taken for granted.
We should be proud of what we fought for and what we were able to achieve.
Together we were able to help change what is possible when it comes to the policies that we care about and the country we want to serve. We released the first comprehensive plan to confront climate change of any of the presidential candidates; we took the boldest approach to gun safety in American history; we confronted institutional, systemic racism and called out Donald Trump for his white supremacy and the violence that he's encouraged against communities that don't look like, pray like or love like the majority in this country; and we were one of the first to reject all PAC money, corporate contributions, special interest donations and lobbyist help.
We proposed an economic program that focused on both equality and equity and would give every American the certainty that one job would be enough; and a healthcare plan that would guarantee that every one of us is well enough to live to our full potential.
We knew the only way our country would live up to its promise is if everyone could stand up to be counted. We released the most ambitious voter registration and voting rights plan, one that would bring 55 million new voters into our democracy, and remove barriers for those who've been silenced because of their race, ethnicity or the fact that they live with a disability.
We spoke with pride about El Paso and communities of immigrants. We elevated the plight and the promise of refugees and asylum seekers. And we proposed nothing short of rewriting this country's immigration laws in our own image, to forever free from fear more than 11 million of our fellow Americans who should be able to contribute even more to our shared success.
And at this moment of truth for our country, we laid bare the cost and consequence of Donald Trump: the rise in hate crimes, the terror attack in El Paso, the perversion of the Constitution, the diminished standing of the United States around the world. But we also made clear the common responsibility to confront him, to hold him accountable and ensure that he does not serve another term in office. Committing ourselves to this task not as Democrats or Republicans, but as Americans first before we are anything else.
I am grateful to each one of you, and to all the people who made up the heart and soul of this campaign. You were among the hundreds of thousands of our fellow Americans who made a donation, signed up to volunteer or spread the word about this campaign and our opportunity to help decide the election of our lifetime.
You have been with me from the beginning, through it all. I know that you did it not for me personally, not for the Democratic Party, but for our country at this defining moment. Though today we are suspending this campaign, let us each continue our commitment to the country in whatever capacity we can.
Let us continue to fearlessly champion the issues and causes that brought us together. Whether it is ending the epidemic of gun violence or dismantling structural racism or successfully confronting climate change before it is too late, we will continue to organize and mobilize and act in the best interests of America.
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 that nominee is.
And proud to call them President in January 2021, because they will win.
We must support them in the race against Donald Trump and support them in their administration afterwards, do all that we can to help them heal a wounded country and bring us together in meeting the greatest set of challenges we have ever known.
I'm confident I will see you down the road, and I look forward to that day.
Thank you for making this campaign possible, and for continuing to believe that we can turn this moment of great peril into a moment of great promise for America and the world.
With you always, and forever grateful.
ABC NEWS contributed to this story.