Former Pennsylvania senator Rick Santorum stands with his wife, Karen, as he formally announced his second GOP presidential bid on Wednesday, hoping to improve on his 11-state run in 2012. (Keith Srakocic/AP)

Rick Santorum, the brusque and deeply conservative former senator who won nearly a dozen contests in the 2012 race for the Republican presidential nomination, announced here Wednesday that he would seek to recapture that magic by entering a crowded primary competition likely to be far more difficult than the last.

The step forward by Santorum, 57, is the latest in a wave of entries by hard-right contenders who believe that after losing two straight presidential elections behind more moderate nominees, GOP voters will turn to a candidate unflinching in ideology who can excite the party’s base.

Sen. Ted Cruz (Tex.), a tea party star, announced his bid in March. This month, neurosurgeon Ben Carson and former Arkansas governor Mike Huckabee — evangelical favorites and regular guests on Fox News — launched campaigns.

But even Santorum, known for his staunch opposition to gay marriage and abortion, has acknowledged that Republicans will need to adapt to the country’s rapidly changing demographics and social views to win back the White House.

Speaking at sunset in Butler County, where he spent parts of his childhood, Santorum did not focus on the socially conservative positions that he passionately championed as a House member and senator in the 1990s. Instead, he fixated on his family’s humble roots and his desire to connect the GOP with working-class people.

“Working families don’t need another president tied to big government or big money,” Santorum said. “Today is the day we are going to begin to fight back.”

The announcement marked the latest comeback attempt by Santorum, who vaulted from relative obscurity in 2012 to win the Iowa caucuses and 10 other states — only to fade into obscurity again after Mitt Romney clinched the nomination.

His entry enlarges an already swelling group of official candidates: By next week, the number of declared Republicans is expected to expand to nine, with former New York governor George Pataki jumping in Thursday and Sen. Lindsey O. Graham (S.C.) due to announce soon. And a half-dozen are poised to do the same, including former Florida governor Jeb Bush.

Santorum struck a defiant tone Wednesday on his return to the political stage, shrugging off naysayers in his party who dismiss his candidacy as an underfunded and last-gasp effort for a politician who until his string of victories in 2012 was a little-known former legislator and who had lost his 2006 Senate race by nearly 18 points.

“I know what it’s like to be an underdog,” Santorum said. “Four years ago, well, no one gave us much of a chance. But we won 11 states.” The audience cheered and raucously waved miniature flags.

This time, Santorum’s strategy centers on reviving his support with conservatives in Iowa, where his victory propelled him up from the bottom of national polls after months of handshakes and grass-roots events.

Former Pennsylvania senator Rick Santorum announced his 2016 candidacy for president in Butler County, Pa. In his speech, Santorum attacked Hillary Clinton's stance on immigration, saying her support of unskilled labor is because "she just wants votes." (AP)

Now, Santorum faces higher expectations in a state where he previously used surprise to his advantage and joins a primary race with starkly different political dynamics: The party establishment does not have a clear front-runner to whom he can play foil, and a younger generation of ambitious Republicans — such as Sen. Marco Rubio (Fla.) — has emerged.

In particular, Huckabee and Cruz occupy the political space that Santorum hopes to again call his own, blending fervent backing from Christian activists, foreign-policy hawks and populist conservatives.

As he begins to navigate the new terrain, Santorum will lack most of the consultants who engineered his 2012 insurgency.

His former campaign manager, Michael Biundo, is working on the campaign of Sen. Rand Paul (Ky.). His former Iowa aide, Chuck Laudner, who drove Santorum around the state in his “Chuck truck,” has signed on with possible candidate Donald Trump. Two former spokesmen are working for Huckabee.

Among those still in Santorum’s camp are longtime confidant John Brabender and wealthy donor Foster Friess, whose money helped lift Santorum’s 2012 bid and who has been working to raise funds for him again.

Brabender said in an interview Wednesday that Santorum has been counted out many times in his career and remains undaunted by his low standing in the polls. But Brabender is irritated by network television rules based on polling averages, which could preclude Santorum from reaching the threshold for participation in the first GOP debate in August.

“They shouldn’t arbitrarily decide if it’s eight, 10, 12, or whatever,” he said. “Rick’s not a senator, he’s not a governor, he doesn’t have his own TV show, and he’s not named Bush.”

Friess refused to say how much he would put behind Santorum. “That’s a private question,” he said as he strolled around the polished shop floor with a black cowboy hat pulled low. “I’m going to keep a very low profile. . . . Right now, I’m giving to Santorum, period.”

There is also likely to be heightened attention on the candidate’s biography, including the struggles that Santorum and his wife, Karen, have had in raising a severely disabled daughter. The couple co-wrote a raw and revealing book, “Bella’s Gift,” this year about the chromosomal condition Trisomy 18, which is rare and lethal.

Santorum has for decades put his large family at the heart of his political life. Here at Penn United Technologies, about 30 miles northeast of Pittsburgh, he appeared on stage alongside his wife and most of their seven children.

Beaming and surrounded by barrels of metalworking lubricants, he spoke of his family’s background in the region, where his Italian immigrant grandfather was a coal miner. At the start, he held aloft a lump of coal.

The setting was both nostalgic and political. While Santorum seeks to craft his persona around his time in Congress as a pugnacious western Pennsylvanian, he lives these days in suburban Northern Virginia and recently managed a small film company.

Gaitha and Steve Athans from Columbia, Mo., two older conservatives donning “Rick” stickers, said they drove hundreds of miles to attend.

“We just had to come,” said Steve Athans, who works at Macy’s as a salesman and has seen friends hurt by the stagnant economy. “Nobody is doing anything for working people, so I want to be part of his army.”

Colby Itkowitz contributed to this report.