As the growing field of presidential candidates competes for attention and money, faith voters remain particularly targeted.

Among the 10 official Republican candidates, about half are explicitly positioning themselves as the candidate for conservative evangelicals.

U.S. Sen. Ted Cruz of Texas announced his presidential run at Liberty University, the school founded by Jerry Falwell that often serves as a key stopping point for Republican presidential hopefuls.

A Southern Baptist whose father is a pastor, Cruz often invokes religion in his campaign.

Author Ben Carson launched his presidential campaign profile by criticizing President Barack Obama at the 2013 National Prayer Breakfast. He peppers his speeches with religious messages.

The leaders of the Southern Baptist Pastors’ Conference sparked controversy for inviting – and then for disinviting – the Seventh-day Adventist to speak at the conference next week.

Two failed candidates from 2012 jumped back in, both hoping to once again excite conservative evangelicals. However, neither enjoys the support that helped them briefly lead the race last time.

Former U.S. Sen. Rick Santorum won Iowa in 2012 largely due to religious appeals, but many of his key supporters now back other candidates

Former Texas Gov. Rick Perry similarly enjoyed the support of conservative evangelicals as he secretly planned his campaign with some and launched his campaign with a mega-prayer rally.

However, his campaign fell apart and he became the most underperforming candidate in modern presidential campaigns.

Although he grew up Methodist and switched to a nondenominational megachurch while governor, Perry was rebaptized last year.

Another returning candidate is former Arkansas Gov. Mike Huckabee, who won Iowa in 2008 with his religious appeals. A former Southern Baptist pastor, Huckabee spent the last several years as a Fox News host.

Despite his past success, 2016 will be a different race as he faces a more crowded field and he has shifted rightward in policies and adopted a more aggressive tone.

Even most of the five declared candidates who are not positioning themselves as primarily the conservative evangelical choice are also using religious appeals.

Only former New York Gov. George Pataki, a Catholic, is remaining mostly quiet about his faith. The least conservative candidate, he currently sits near the bottom of the polls.

U.S. Sen. Marco Rubio of Florida remains popular with many conservative evangelicals but attempts to create a broader image.

A Catholic, he was Mormon for a few years as a child and attended a Southern Baptist church for a few years as an adult.

He brings religion into his campaign speeches with ease, particularly trumpeting claims of Christian persecution.

U.S. Sen. Rand Paul of Kentucky, a graduate of Baylor University, grew up Episcopalian but is now a Presbyterian.

He talks about religion in some in his speeches, but is running more as a libertarian challenge to establishment Republican positions.

“My faith has never been easy for me, never been easy to talk about and never been without obstacles,” Paul said in 2012. “I do not and cannot wear my religion on my sleeve. I am a Christian but not always a good one. I’m not completely free of doubts.”

Despite his hesitancy to talk about religion, Paul will release a book this fall called “Our Presidents & Their Prayers: Proclamations of Faith by America’s Leaders.”

A third Southern Baptist in the race, U.S. Sen. Lindsey Graham, hails from a key early state where conservative evangelicals often impact the race: South Carolina.

His pastor, Tim Tate of Corinth Baptist Church in Seneca, prayed at the start of his campaign announcement.

A more moderate candidate in the race primarily pushing foreign policy issues, Graham does not use religious rhetoric as much as most of his opponents.

His positions on immigration, climate change and other issues often spark criticism from Tea Party conservatives.

In 2008, Graham was scheduled to speak at the Celebration of a New Baptist Covenant organized by former President Jimmy Carter, but he missed the event while helping U.S. Sen. John McCain win the Republican presidential nomination that year.

Huckabee also originally agreed to speak at the event but reneged over a political dispute.

Former Hewlett-Packard CEO Carly Fiorina has tweaked her public religious persona as she seeks the presidential nomination.

During her failed 2010 U.S. Senate campaign in California, the New York Times described her as “an irregular churchgoer, not devoted to any denomination.”

Five years later, she works her faith into speeches as she seeks electoral support in more evangelical states like Iowa.

Over the past few months, Fiorina has talked about growing up in an Episcopalian church, expressed her opposition to same-sex marriage in religious terms, and credited her “personal relationship with Jesus Christ” for helping her after she lost a daughter to addiction.

Other Republicans considering running – but not yet in the race – include former Florida Gov. Jeb Bush, Louisiana Gov. Bobby Jindal, Ohio Gov. John Kasich, business mogul Donald Trump and Wisconsin Gov. Scott Walker.

If they enter, each will likely join the other candidates in making God-based appeals. Even Trump reached out to conservative evangelicals as he flirted with running during the 2012 campaign.

On the Democratic side, the religious appeals are less frequent among the four declared candidates.

Two candidates – Vermont U.S. Sen. Bernie Sanders (a nonreligious Jew) and former Rhode Island Gov. Lincoln Chafee (an Episcopalian) – are expected to remain virtually silent on personal faith matters.

Former Maryland Gov. Martin O’Malley has not yet talked about religion much in his short campaign, but often mentioned his Catholic faith in the past.

Democratic Maryland state Sen. Jim Rosapepe called O’Malley “a social justice Catholic – or, as some have called him, a Pope Francis Democrat – in the tradition of Mario Cuomo and Robert Kennedy.”

The Democratic frontrunner, former U.S. Secretary of State Hillary Clinton, will likely join O’Malley in talking some about faith.

Clinton, a Methodist, often used religious references during her 2008 presidential campaign, but some campaign watchers expect her to invoke religion less during this presidential run.

With so many candidates running – and several courting Christian voters – churches in key states may face many temptations over the next several months to turn their pulpits over to a presidential hopeful.

Brian Kaylor is a contributing editor for EthicsDaily.com and the author of an award-winning book of religion and politics, “Presidential Campaign Rhetoric in an Age of Confessional Politics.” You can follow him on Twitter @BrianKaylor.