Potential Republican presidential candidate Jeb Bush is seeking to increase his appeal among evangelical Christians with a commencement speech at Liberty University. (Reuters)

Likely presidential candidate Jeb Bush called on fellow Christians to stand up for their values and against what he described as a federal government meddling in matters of faith, making a direct appeal to religious conservatives in a speech at Liberty University Saturday.

Delivering the commencement address at the booming evangelical university launched by Moral Majority founder Jerry Falwell, Bush referred to a group of nuns who fought a birth control mandate under the Affordable Care Act.

“I don’t know about you, but I'm betting that when it comes to doing the right and good thing, the Little Sisters of the Poor know better than the regulators at the Department of Health and Human Services,” Bush said. “From the standpoint of religious freedom, you might even say it’s a choice between the Little Sisters and Big Brother. And I’m going with the Little Sisters.”

Not yet an official candidate for president, the former Florida governor was making what has become an essential campaign stop for Republicans seeking the White House by speaking at Liberty.

“How strange, in our own time, to hear Christianity spoken of as some sort of backward and oppressive force,” Bush said before a crowd of about 34,000 in the campus stadium, adding, “. . . I cannot think of any more subversive moral idea ever loosed on the world than, ‘The last shall be first, and the first last.’”

Republican U.S. presidential hopeful and former Florida governor Jeb Bush quietly began reaching out to evangelicals about a year ago. (Alex Wong/Getty Images)

Bush also touched on the topic of abortion in his 30-minute speech, saying, “Wherever there is a child that is waiting to be born, we say, ‘Choose life,’ and we say it with love.”

He did not mention same-sex marriage, a divisive and risky topic for a possible GOP candidate because opinion polls show a majority of older voters in the party oppose it while a majority of younger voters are in support.

Bush made only a playful reference to his presidential ambitions, as he mentioned meeting Jonathan Falwell, a Lynchburg pastor who is the son of Liberty’s founder and the brother of its current president.

“His dad used to be president, then his brother became president. Somehow -- I don’t know what it was -- we really hit it off,” Bush deadpanned. “I’m not sure what’s in store for you Jonathan, but I’m pulling for you, man.”

Of the dozen or so declared or likely GOP presidential contenders, Bush might seem the most out of place on the conservative campus in the foothills of Virginia’s Blue Ridge Mountains. Despite his conversion to Catholicism and opposition to abortion, Bush is viewed warily by his party’s right flank for his relatively moderate views on immigration and Common Core educational standards and for his failure to take as hard a line in his opposition to same-sex marriage as some of the rest of the GOP field.

The son and brother of former presidents, Bush is an establishment favorite whose appearance at Liberty represents one of his most conspicuous efforts yet to woo evangelicals.

“I think it’s smart of him to go to Liberty,” said Richard Cullen, who was appointed U.S. attorney for the Eastern District of Virginia in 1991 by President George H.W. Bush and served on George W. Bush’s legal team during the Florida recount in 2000.

“Jeb has attracted a lot of business leaders who think he is a winner and a really sharp guy, and they’re willing to support him,” said Cullen, now chairman of McGuireWoods, the Richmond-based legal and lobbying powerhouse. “Nobody ever accused him of not being a conservative until recently, and I think he will survive any scrutiny. . . . He’s a very spiritual and religious person.”

But Bush has a long way to go to win over some religious conservatives. Some were particularly irked by his reaction in January, when Florida began allowing same-sex marriages. Bush issued a statement that reiterated his support for religious liberty but also urged respect for “the rule of law” and for “couples making lifetime commitments to each other.”

“I’m skeptical,” said Brian Brown, president of the National Organization for Marriage, who noted that Bush’s top political adviser, David Kochel, has advocated for same-sex marriage. “We need to be a party that welcomes people back into the fold when they make mistakes, but it’s going to take a lot. And an appearance at Liberty is not going to cut it.”

Many in the audience said they were impressed with Bush.

“It was good to hear of his Christian faith and that he’s so strong in that,” said Gwendi Smart, 60, who had traveled from her home in central New York to watch her daughter-in-law receive her diploma.

“You don’t know that from listening to the news,” she said, adding, “Of course, I watch Fox.”

“He was on the spot talking about how as Christians, we have to go out and stand up for what we believe in,” said Natalie Sightler, 32, a Virginia Beach mother of two who received a master’s degree in education.

In his speech, Bush praised the power of Christianity in action.

“Today, by the thousands, Liberty is sending forth across America civilized, confident, true-hearted men and women — which happens to be just what America needs,” Bush said to the crowd, which included 6,200 graduates in attendance.

“This doesn’t always come as a welcome reminder in some quarters, but it is true all the same: Whatever the need, the affliction, or the injustice, there is no more powerful or liberating influence on this earth than the Christian conscience in action,” he said.

He rejected the notion of religious Americans as “intolerant scolds.” He praised Pope Francis and played up acts of faith that could also appeal to liberals: serving the poor, “giving hope to the prisoner,” defending women and girls against exploitation abroad, and protecting the environment.

“Christians see in nature and all its creatures designs grander than any of man’s own devising - the endless, glorious work of the lord of life,” he said, using language that could speak especially to evangelicals. He praised young people working as “protectors of creation.”

Bush quietly began reaching out to evangelical leaders about a year ago. But he has not made many public gestures to them. He skipped an Iowa faith group’s recent summit and several similar events, though the bilingual former governor — who has made Latino outreach a major focus — did appear 10 days ago at the National Hispanic Christian Leadership Conference in Houston.

Bush’s scheduled visit to Liberty is a more overt effort to win the Christian right. It comes less than two months after Sen. Ted Cruz (R-Texas) chose the campus to announce his own bid for the presidency — and at the end of a week that saw the Republican field swell by three.

Former Hewlett-Packard executive Carly Fiorina, retired neurosurgeon Ben Carson and former Arkansas Gov. Mike Huckabee all jumped into the race this week, joining two others already on the trail: Sen. Rand Paul (R-Ky.) and Sen. Marco Rubio (R-Fla.). That’s on top of another half-dozen likely but undeclared candidates.

Many of those are expected to find their way to Liberty, whose thrice-weekly convocation speeches — mandatory for the nearly 14,000 on-campus students — guarantee an impressive crowd.

“Several of them are figuring out right now, when is their Liberty appearance?” said Victoria Cobb, president of the Family Foundation of Virginia.

In the current and recent election cycles, Liberty has hosted a parade of Republican presidential hopefuls, including Sen. John McCain of Arizona, former Massachusetts governor Mitt Romney, former governor Rick Perry of Texas, former congresswoman Michele Bachmann of Minnesota, Huckabee, former Speaker of the House Newt Gingrich, Paul and his father, former congressman Ron Paul. Louisiana Gov. Bobby Jindal, a likely 2016 contender, was last year’s commencement speaker.

The appearances have been strained at times. McCain came to campus in 2006, as he prepared for his 2008 bid, after calling Falwell and televangelist Pat Robertson “agents of intolerance.” And evangelicals had their doubts about Romney, a Mormon, who was the commencement speaker in 2012.

What started as a tiny Bible college in 1971 has grown into a university with a law school, medical school and massive online education venture. Online enrollment tops 95,000, making Liberty the largest private, nonprofit university in the nation and the largest Christian university in the world.

It is not just Liberty’s size, but its bent, that makes it a big draw for Republican contenders. The school’s motto is “Training Champions for Christ.” The campus is dry, its dorms single sex. And its students are politically active.

“We’ve always attracted very conservative [students and faculty], just like Harvard attracts students and faculty who might be more on the other side of the political spectrum,” Liberty President Jerry Falwell Jr., the son of the school’s late founder, said in an interview.

As if there were any doubt about Liberty’s stature in the world of conservative politics, Falwell alerted the crowd to two other big names connected with the event. Bachmann was in the audience to see her daughter collect a degree. And Fox News personality Sean Hannity would have been there to do the same for his wife, but she was ill and could not attend,

As a nonprofit, the school does not make endorsements. Falwell said its doors are open to politicians of all stripes.

Virginia Gov. Terry McAuliffe (D) had been scheduled to speak at Liberty on March 23 before Cruz asked to kick off his campaign on that date. Falwell said the governor was still welcome, but he opted to reschedule.

Liberty invited then-Sen. Barack Obama to speak during his first run for president in 2008. He instead sent a surrogate, then-Gov. Timothy M. Kaine (D). Sen. Mark Warner (D-Va.) spoke in March 2014.

“We almost went out of our minds when he [the elder Falwell] invited Ted Kennedy and Jesse Jackson,” said Wendell Walker, the GOP’s 6th Congressional District chairman, who enrolled at Liberty in 1975.

Walker described the 1980s-era visits by Kennedy and Jackson as “very cordial.”

“Hillary Clinton is more than welcome to come speak,” Walker said, “although I doubt that’s ever going to happen.”