Former Representative Beto O'Rourke of Texas is dropping out of the presidential race, ending a campaign in which he struggled for months to recapture the energy of his insurgent 2018 Senate candidacy on a national stage full of other big personalities and liberal champions.
Mr. O'Rourke made the decision to quit the race in the middle of this week, on the eve of a gathering Friday of Democratic presidential candidates in Iowa, according to people familiar with his thinking. He is not expected to run for any other office in 2020, despite persistent efforts by party leaders and political donors to coax him into another bid for the Senate.
His campaign has been under extreme financial strain, and Mr. O'Rourke's advisers concluded that proceeding in the race might have meant making deep cuts to his staff in order to pay for advertising and other measures to compete in the early primary and caucus state.
Mr. O'Rourke planned to announce his withdrawal from the race in Iowa on Friday evening and follow up with an email message to his supporters. In that message, a draft of which was reviewed by The New York Times, Mr. O'Rourke said he was proud of championing issues like guns and climate change but conceded that his campaign lacked "the means to move forward successfully."
"My service to the country will not be as a candidate or as the nominee," he said.
By leaving the race, Mr. O'Rourke completes the winding path from his early status as a potential front-runner to his drastic decision over the summer to reframe his candidacy as an activist crusader following the mass shooting targeting Latinos in his home city of El Paso.
Since then, Mr. O'Rourke has campaigned doggedly on issues related to guns and race, calling most notably for federal gun-control policies that would require owners of assault-style weapons to surrender them to the government. That's a far more aggressive stance than most Democratic presidential candidates have endorsed.
That last phase of his campaign has taken Mr. O'Rourke far beyond the early-state circuit, and included visits with prison inmates in California and an immigrant community in Mississippi. In an August interview following the El Paso massacre, Mr. O'Rourke said his focus would be "taking the fight to Donald Trump" and "being with those who have been denigrated and demeaned."
In recent weeks, he has also criticized other Democrats in newly strident terms, declaring in September that Senator Chuck Schumer, the New York Democrat and Senate minority leader, had accomplished "absolutely nothing" on gun control.
Mr. O'Rourke entered the 2020 primary in the middle of March with the aura of a celebrity, cheered by rank-and-file Democrats and admired by no less a figure than former President Barack Obama for his near miss challenge to Senator Ted Cruz in the nation's largest red state. He effectively unveiled his run for the White House in a cover story for Vanity Fair in which he declared he was "just born to be in it." He later described the cover, along with his choice of words, as a mistake.
In the earliest days of his campaign, Mr. O'Rourke was a fund-raising powerhouse, collecting more than $6 million in his first day as a candidate. But his fund-raising cratered almost immediately. He raised more in his first 48 hours than in the following thousand days, and steadily depleted his campaign treasury by spending more than he was taking in.
