Former Starbucks chief executive Howard Schultz said he found it tougher than he expected to capture the attention of moderate voters. (Richard Drew/AP)

Former Starbucks chief executive Howard Schultz formally abandoned his pursuit of an independent campaign for president Friday, telling his supporters in a letter that he found it tougher than he expected to capture the attention of moderate voters and that he didn’t want to risk reelecting President Trump.

Schultz’s decision, after spending months away from public life because of health issues, will come as a relief to Democratic leaders, who feared an independent candidacy by a self-funded billionaire would hobble their eventual nominee. Despite growing frustration with the country’s politics, his aborted run serves as a cautionary tale about the resiliency of the country’s two-party political system.

In a three-page letter to supporters, Schultz outlined his reasons for abandoning his presidential bid and sketched his plans for the future. Moderate voters, who he hoped would be his constituency, have “largely tuned out of political life,” he wrote, and many other potential supporters would not back him because of their concern that he would aid Trump’s reelection.

The calendar also worked against his ambitions, complicating Schultz’s commitment to withdraw his candidacy before a general election if a centrist like former vice president Joe Biden won the Democratic nomination.

“If I went forward, there is a risk that my name would appear on ballots even if a moderate Democrat wins the nomination, and that is not a risk I am willing to take,” he wrote.

Schultz, 66, burst on the political scene in January, when he announced on CBS’s “60 Minutes” that he was considering an independent campaign, days after the news broke that his advisers were exploring the possibility of a third-party run.

His campaign was premised on the notion that a large, moderate plurality in the country felt abandoned by the Republican and Democratic shift toward angrier, more partisan politics and more extreme positions. He also assumed that it was likely that a “far left” candidate would capture the Democratic nomination.

“Eighty-four percent of Americans do not consider themselves far right or far left,” Schultz wrote to supporters Friday. “Among them are an exhausted majority who want common sense, collaborative and truthful government.”

Nine months after he publicly floated the idea of running, Schultz conceded that reaching that “exhausted majority” had proved difficult.

In the first weeks of his effort, which coincided with a national book tour, Schultz received broad media coverage but struggled to turn that attention into a devoted following. He also juggled a fierce backlash from Democrats.

“Here is what is going to happen: He is going to spend hundreds of millions of dollars, and he is going to get into September or October of 2020, and he is going to realize he can’t win,” Jim Messina, President Barack Obama’s 2012 campaign manager, predicted. “He is going to endorse the Democrat or he will accidentally elect Donald Trump.”

Trump, meanwhile, seemed to dare Schultz to get into the race. “Howard Schultz doesn’t have the ‘guts’ to run for President!” Trump tweeted after the “60 Minutes” announcement.

In his letter, Schultz alluded to those challenges, lamenting that “extreme voices currently dominate the national dialogue, often with a vitriol that crowds out and discourages thoughtful discussions.”

Schultz also noted that he has been recuperating from three recent back surgeries that have prevented him from touring the country.

His letter announcing his decision not to run was tinged with an irony: Schultz maintained that the window for a moderate, reasoned third-party candidate was wide open. But he could not figure out how to grab and hold voters’ attention in an electoral cycle dominated by angry, partisan voices.

“We don’t have to look far to see proof that empathy, respect and civility run deep,” he wrote. “But not in Washington D.C.”

As he prepared for a campaign, Schultz hired a number of experienced political professionals, including Steve Schmidt, John McCain’s 2008 presidential campaign manager; Bill Burton, a former top aide to Obama; and pollster Greg Strimple.

He also put on retainer a team that was planning a 50-state effort to get his name on the presidential ballot in 2020.

Schultz repeatedly brushed off criticism that his presidential run was driven by vanity, insisting that he would withdraw from the race if he risked reelecting Trump.

“Trump must not serve a second term,” he said in February. “As I explore whether to run for office, I will do so with the conviction that my final decision must not make his reelection a possibility. . . . No one wants Donald Trump fired more than I.”

During a tenure as the chief executive of Starbucks, which ended in 2018, Schultz cast himself as a compassionate leader who wanted to use his company for social good. He earned praise for the benefits Starbucks provided its retail workers, including a stock ownership plan, health-care coverage options for part-time employees and the opportunity to attend college online at no cost.

When Trump announced a ban on U.S. visitors from seven predominantly Muslim countries in January 2017, Schultz announced a company goal of hiring 10,000 refugees in stores around the world.

As a politician, he promised to operate free from party orthodoxy, saying as president he would not sign any legislation that did not have bipartisan support and that he would seek to have his Supreme Court nominees approved by two-thirds of the Senate.

He promised to “go after” government expenditures in Social Security and Medicare and called for raising taxes on the wealthy, but he also denounced liberal calls for a new tax on wealth or a return to 70 percent tax rates for those in top income brackets.

Schultz, whose wealth is estimated at more than $3 billion, was stung by the angry and personal nature of the criticism that came at him as he weighed whether to run. In ending his run, he urged Americans “not to become hopeless or complacent.” He vowed to use the money he had planned to commit to the campaign to invest in people and organizations that promote ideas to “move the country beyond two-party gridlock.” He also pledged to work to improve access to “a truly magnificent future.”

It’s unclear whether that will include encouraging other independent or third-party candidates.

The last time a third-party presidential candidate won individual states was in 1968, when former Alabama governor George Wallace picked up 46 electoral college votes in the South on the American Independent Party ticket. Republican Richard M. Nixon nonetheless won that election, and third-party bids have been blamed by partisans since then for affecting election results.