WASHINGTON – Beto O’Rourke, the former Texas congressman, announced Friday that he was ending his Democratic presidential campaign, which failed to recapture the enthusiasm, interest and fundraising prowess of his 2018 Senate race.

In an online post, O’Rourke said, “My service to the country will not be as a candidate or as the nominee.” He was scheduled to address supporters later Friday at an event in Iowa.

O’Rourke was urged to run for president by many Democrats, including supporters of former President Barack Obama, who were energized by his narrow Senate loss last year in Texas, a reliably Republican state. He raised an astonishing amount of money from small donors across the country, visited every county in Texas and used social media and livestreaming video to engage directly with voters. He ultimately lost to incumbent Republican Sen. Ted Cruz by 3 percentage points.

But O’Rourke struggled to replicate that model in the presidential primary, and both his polling and his fundraising dwindled significantly in recent months.

“Though it is difficult to accept, it is clear to me now that this campaign does not have the means to move forward successfully,” he wrote on Medium. “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.”

O’Rourke’s decision comes as the Democratic primary enters a critical stretch. With three months until the kickoff Iowa caucuses, polls consistently show a trio of candidates leading the way: former Vice President Joe Biden, Massachusetts Sen. Elizabeth Warren and Vermont Sen. Bernie Sanders, with Pete Buttigieg, the mayor of South Bend, Indiana, showing strength in Iowa, as well. Lower polling candidates face difficult questions about whether they have the money to sustain a campaign through the first primary contests.

Earlier this week, Kamala Harris, another candidate who entered the race to much fanfare, announced she was downscaling her campaign, laying off some staffers and reorienting almost exclusively to focus on Iowa.

O’Rourke entered the race as the feel-good, dynamic candidate who had the ability to appeal to both Republicans and Democrats and work across the aisle in Washington. But he immediately faced criticism that he had a sense of entitlement, particularly after the release of a Vanity Fair interview on the eve of his campaign launch in which he appeared to say he was “born” to be in presidential politics.

He also struggled with consistent vision and messaging as a presidential candidate.

He spent several weeks trying to build his campaign around climate change, calling global warming the greatest existential threat the country had ever faced. After a gunman opened fire at a Walmart in his hometown of El Paso, killing 22 people, O’Rourke more heavily embraced gun control, saying he would take assault weapons away from existing owners.

O’Rourke did not endorse another Democrat for the nomination, saying the country will be well served by any of the other candidates, “and I’m going to be proud to support whoever that nominee is.”

President Donald Trump quickly weighed in on O’Rourke’s exit, saying in a tweet: “Oh no, Beto just dropped out of race for President despite him saying he was “born for this.” I don’t think so!”