GREENVILLE, S.C. (AP) -- Republicans making their pitch to be the party's 2016 presidential nominee aimed to out-do each other Saturday in arguing that President Barack Obama is a failed leader.

But hitting Obama with the usual critiques - from his 2010 health care overhaul to allegations of missteps on foreign policy to the rise in the national debt during his time in office - also made it hard for the gaggle of White House aspirants to stand out during a forum in South Carolina hosted by the conservative group Citizens United.

Wisconsin Gov. Scott Walker tried by touting his ability to beat whomever is nominated by the Democratic Party, reminding activists that he won three statewide elections in four years in a state twice carried by Obama.

"The last time a Republican carried the state for president was 1984," he said. "That's a tough state."

He even took the crowd back to his decision to run for county executive in heavily Democratic Milwaukee County. "Never ever had there been a Republican in that spot before," he said.

Carly Fiorina, the former Hewlett-Packard CEO, continued her tactic of going straight at Hillary Rodham Clinton, the Democratic favorite for 2016. "She is not trustworthy, and she does not have a record of accomplishment," Fiorina said.

In an interview before his turn on stage, Louisiana Gov. Bobby Jindal pointed to his work on policy, saying he's the only potential candidate in the field who has "spent the last 18 months coming up with detailed ideas on health care, on foreign policy, on energy."

Once on stage, Jindal spent considerable time touting his credentials as a social conservative, including his pushback against criticism from some in the business community over "religious liberty" laws that have become a flashpoint in the national debate over same-sex marriage.

"Don't even waste your breath trying to bully the governor of Louisiana," Jindal said, repeating what he said was his message to corporate leaders.

Rick Santorum, who won the Iowa caucuses in 2012 before fizzling out against eventual nominee Mitt Romney, warned that Republicans eager to retake the White House after Obama's two terms in office must stay focused on reaching working-class voters.

"We have to be a pro-worker party," he said. "We have to be the party for a rising tide lifting all boats. There are millions and millions of Americans who have holes in those boats."

Florida Sen. Marco Rubio took a hard line on foreign policy, saying the nation must get tougher with terrorists. Adapting a line from the movie "Taken," he said: "We will look for you. We will find you. And we will kill you."

Texas Sen. Ted Cruz trumpeted his unapologetic approach on Capitol Hill, where he helped engineer a partial government shutdown in 2013. And he told activists that they should compare his style with his rivals, all of whom insist they are conservative.

"Have you had anyone up here today say, 'I'm an establishment moderate who stands for nothing?'" he said. "So how do you tell the difference? The scriptures tell us, 'You shall know them by their fruits." That means, he said, asking candidates, "You say you believe these principles. When have you fought for them?"

Former Texas Gov. Rick Perry let loose a series of broadsides at Obama and his policies, drawing cheers from the crowd for a withering critique that covered immigration, the Affordable Care Act, the Islamic State militant group and the federal budget.

His bottom line: "We've seen gross incompetence. We're here to declare that we're not going to take it anymore."

Ben Carson, the retired neurosurgeon who, like Fiorina, announced his candidacy earlier this week, is running as the outsider. "I'm not a politician," he said. "That's what sets me apart."

Those not in South Carolina on Saturday included former Florida Gov. Jeb Bush, who delivered the commencement address at Liberty University in Virginia; Kentucky Sen. Rand Paul, who was campaigning in northern California; and former Arkansas Gov. Mike Huckabee, who was in South Carolina on Friday.

Citizens United President David Bossie dismissed the idea that the large number of GOP candidates muddled their messages and called the wide field an advantage.

"These men and women all believe in American exceptionalism," Bossie said. He added that along with criticizing Obama, Republicans should focus their ire on Clinton - a point on which many in the crowd agreed.

"Any one of them would be better than the disaster we've got now," said Gary Gunderson of Abbeville, South Carolina. His wife, Margaret, chimed in: "Or Hillary."