Conservative culture warrior Rick Santorum launched a 2016 White House bid on Wednesday, vowing to fight for working-class Americans in a new election season that will test his influence — and focus on social issues — in a changing Republican Party.

The former Pennsylvania senator may have exceeded his own expectations by scoring a second-place finish in the race for the Republican presidential nomination four years ago. Yet as he enters a more powerful and diverse 2016 field, he may struggle even to qualify for the debate stage in his second run.

“I am proud to stand here, among you and for you, the American workers who have sacrificed so much, to announce that I am running for president of the United States,” the 57-year-old senator said, flanked by factory workers and six of his seven children in a cinderblock warehouse near his western Pennsylvania hometown.

“The last race, we changed the debate. This race, with your help and God’s grace, we can change this nation.”

Santorum opens this political season as a heavy underdog in a race expected to feature more than a dozen high-profile Republicans — most of them newcomers to presidential politics. He is among the nation’s most prominent social conservatives, having dedicated much of his political career to opposing same-sex marriage and abortion rights, while advocating for conservative Christian family values.

He mentioned cultural issues briefly Wednesday in remarks designed to broaden his appeal to working-class Americans. “As president, I will stand for the principle that every life matters — the poor, the disabled and the unborn,” said Santorum, a Catholic.

He ultimately won 11 states in the GOP’s 2012 primary election after an unexpected and narrow victory in the opening contest in Iowa, where he emerged as a conservative favorite after touring the state’s 99 counties in a pickup truck.

His road to relevancy this time won’t be easy.

“It’s going to be much more competitive,” said Foster Friess, a prominent donor who was standing near the podium during Wednesday’s announcement.

Santorum has acknowledged his challenges in 2016, but says his experience could pay dividends the second time around. Most of the GOP’s recent presidential nominees, Mitt Romney and President Ronald Reagan among them, needed more than one campaign to win the nomination.

He faces considerable competition for his party’s social conservatives in particular. The list of Republicans already courting religious voters includes former Arkansas Gov. Mike Huckabee, a Baptist pastor who won the Iowa caucuses in 2008, former Texas Gov. Rick Perry, Louisiana Gov. Bobby Jindal and Texas Sen. Ted Cruz. And like Santorum, former Florida Gov. Jeb Bush is a Catholic.

Polling suggests a shift in voter attitudes about the importance of social issues, particularly gay marriage, which has long been a defining issue for Santorum. Like others in his party, he has appealed to religious voters recently by criticizing what he calls President Barack Obama’s “war on religious freedom,” which includes the broader debate over whether private businesses can deny services to same-sex couples.

Santorum promised Wednesday to “fight for the freedom for you to believe what you are called to believe, not just in your places of worship, but outside your places of worship, too.”

His longshot status may keep him out of presidential debates altogether.

Only those who place in the top 10 of national polls will be allowed to participate in the first Republican presidential debate in August, according to guidelines released by network host Fox News. Santorum is on the bubble.

While advisers suggest he will benefit from a donor network that has grown in recent years, questions remain about Santorum’s ability to raise money as well.

Friess, who previously gave more than $2 million to a pro-Santorum super PAC in 2012, said he would continue to support Santorum’s White House ambitions, although he plans to avoid donating large amounts directly to the campaign or a supportive super PAC, both of which would disclose their donors.

“Any giving I’m doing is going to be lower-profile and less noticed,” Friess told The Associated Press.

Santorum immediately launches a rollout tour that begins in Iowa on Thursday and Friday and moves to South Carolina on Saturday and Sunday. He is not scheduled to appear in New Hampshire, where voters typically don’t favor candidates who focus on social issues.

A crowd of hundreds watched Santorum’s announcement at Penn United Technologies, an employee-owned manufacturing company based in the western Pennsylvania county where Santorum grew up.

Wallace Cypher, 54, who lives a half mile away, said he’s backing Santorum because he wants a true conservative to win the GOP presidential nomination.

“I think he’d be a whole lot better than what we’ve got in there right now,” Cypher said.

(AP)