Rick Santorum’s journey did not take him to the White House. But it represented a stunning turnaround for the former senator from Pennsylvania, who rose from being a political castoff to reshape the Republican presidential race and resurrect his political fortunes.

Virtually no other candidate began the campaign from a lower perch. Santorum was a social conservative in a race expected to center on the economy. He was famous for his hard-edged brand of conservatism, especially his remarks on homosexuality, and for losing his Senate seat by an embarrassing 18 points in 2006. He was so discounted that he struggled to get the attention of debate moderators.

Yet Santorum outlasted most of his competition, winning the Iowa caucuses and contests in 10 other states — a historic feat for an upstart badly outgunned by the front-runner, Mitt Romney, who raised $74 million, more than four times Santorum’s $15.6 million. Ralph Reed, founder of the conservative Faith and Freedom Coalition, called the achievement “remarkable.”

“He got into the race with virtually no endorsements, very little money, and he was an asterisk in the polls,” Reed said. “And he ends the race having won 11 states and over 3 million votes, which is the most since any insurgent conservative candidate since Reagan.”

Santorum’s decision Tuesday to suspend his campaign was a concession to the reality that Romney, who has won 660 convention delegates to Santorum’s 281, had accumulated a virtually insurmountable lead, and that he risked losing much of the cachet he had built up by staying in the race too long and becoming a spoiler.

Hogan Gidley, a spokesman for the campaign, said Santorum no longer saw a realistic path to win the nomination and decided Monday night to end his bid. For weeks, the campaign had been saying he had to win Pennsylvania, something his advisers still believed he would have done; Newt Gingrich had to drop out of the race so that Santorum could take his delegates; and Texas had to change its rules so that the winner of its primary got all 155 of the state’s delegates. The latter two did not seem imminent.

“There was no way to have the proper amount of delegates to move on,” Gidley said. “It was time to look for other avenues to beat Barack Obama.”

He said that Santorum “made no promises” to endorse Romney but that he agreed to meet with the former Massachusetts governor, who called him Tuesday.

By pulling out before the April 24 primary in Pennsylvania, Santorum may have averted another humiliating loss in his home state. The decision also came on the heels of the most recent hospitalization of Santorum’s youngest daughter, Bella, who has a chromosomal disorder.

Santorum is now positioned to play a new role in politics. While few expect Romney, the presumptive nominee, to choose Santorum as his running mate after such an acrimonious primary fight, his supporters believe that he may be poised for a Cabinet post. And at 53, he could be a formidable candidate for president in 2016.

Santorum came this far not only by waging an unusually emotional campaign but by carrying out a clever strategy that began more than a year ago in Iowa.

He spent a year campaigning in the state, shifting his family of nine there and trundling from county to county in a vehicle he dubbed “the Chuck Truck,” after an aide. He made up for his lack of official endorsements with a bus full of reality-TV backers: Jim Bob and Michelle Duggar and their 19 children, who often showed up at his campaign rallies.

After winning the Iowa caucuses — belatedly, after a recount — he quickly pivoted to states where he could demonstrate momentum. He did so by sweeping the Feb. 7 contests in Minnesota, Missouri and Colorado.

But his campaign faltered when he attempted a head-to-head matchup on Romney’s native turf, Michigan. He narrowly lost the primary there as well as one in Ohio, and those defeats deflated his contention that he would be more competitive against President Obama in the Rust Belt.

Santorum, who prided himself on a shoestring campaign that lacked a professional pollster, struggled against Romney’s better-organized and better-funded operation. He made gaffes and often failed to stay on message. And he was never able to convince voters that he could appeal to independents — a necessity in the general election.

“Santorum was just the underdog who went out there and connected with folks,” said Ed Rollins, a veteran GOP strategist who has managed presidential campaigns. “But there’s a long history of candidates who gain in momentum, and then their momentum catches up to their lack of organization, and they get done in.”

While in Congress, Santorum gained a reputation as a passionate but sometimes caustic advocate for his causes. Though that persona sometimes peeked through on the campaign trail — for example, when he cursed at a reporter — it was a different Santorum that shone for most of the race: humble, likable and earnest. The image was reinforced by the anachronistic sweater vest that became his signature garment.

Santorum’s unusual, emotionally driven run will probably have reverberations for the rest of the race. By connecting with evangelical Christians and other deeply conservative Republicans, he exposed Romney’s chronic difficulties in winning over those voters. And by invoking his blue-collar roots, he put a face on the struggles of people who work in the manufacturing sector.

Despite the country’s economic focus, Santorum, a staunch Catholic, rose on a message that centered on a conservative vision of family. He argued passionately that the nation could not shed its economic troubles without shoring up heterosexual marriage, ending abortion, and returning God and religion to the center of public life.

His decision to suspend his campaign prompted an outpouring of plaudits from socially conservative groups. Tony Perkins, president of the Family Research Council, praised Santorum’s “boldness and tenacity,” and the Susan B. Anthony List, a conservative women’s group, credited him with reenergizing the anti-abortion movement.

In his remarks Tuesday, Santorum acknowledged the unlikely trajectory of his campaign and ruminated on what he thought his strengths had been.

“People say: ‘How did this happen? How were we able to come from nowhere?’ ” he said. “It’s because I was smart enough to figure out that if I understood and felt at a very deep level what you were experiencing across America and try to be a witness to that, try to be in a sense an interpreter of that, that your voice could be heard, and miracles could happen.”