Faced with stiff competition for the social conservative vote, Sen. Ted Cruz is kicking his assault on Planned Parenthood into high gear this week with the launch of an ambitious 50-state campaign to end taxpayer support for the women’s health organization.

The Texas lawmaker and Republican presidential candidate has invited 100,000 pastors to participate in a conference call Tuesday about how to defund Planned Parenthood following the release of several sting videos that were shot and edited by an anti-abortion group. In the videos, Planned Parenthood executives are seen casually discussing the process of donating fetal tissue for medical research.

Planned Parenthood maintains that it does not profit off such donations and that any money exchanged goes to covering the costs involved with the handling and transfer of the material. But Cruz has repeatedly called for a federal investigation into the matter and pledged to prosecute Planned Parenthood as president.

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In an emailed invitation, which was distributed by the American Renewal Project – an organization of conservative pastors run under the sponsorship of the American Family Association (AFA), a designated hate group – Cruz called Planned Parenthood’s fetal tissue donation practices “barbaric” and accused the organization of selling body parts “to the highest bidder.”

“As the son of a pastor, I know you bear a high and holy calling on your lives,” Cruz says in the email, which was published in full by CBN News. “I am urging you to confront this evil in our nation by praying and preaching with an unbridled passion until funding for Planned Parenthood ends, and this barbaric practice is purged from the land.”

The plan calls for two weeks of mobilization efforts aimed at encouraging churchgoers to put pressure on their elected representatives to defund Planned Parenthood. Earlier this month, the U.S. Senate failed to advance a Republican-sponsored bill that would’ve stripped the women’s health organization of the more than $500 million it receives in federal funding. Now, Cruz is apparently enlisting pastors in the effort and providing them with an outline they can use when preaching about “the shedding of innocent blood.”

“The battle we face is not political. It is spiritual,” Cruz says in the email. “To enter this arena in a prayerless condition invites failure.”

Cruz is facing a competitive primary field of several socially conservative presidential candidates, and this latest offensive against Planned Parenthood could help separate him from the likes of Louisiana Gov. Bobby Jindal, former Arkansas Gov. Mike Huckabee, and real estate mogul Donald Trump – the current GOP frontrunner. The campaign’s launch follows Cruz’s “Rally for Religious Liberty” on Friday in Des Moines, Iowa, where the White House hopeful courted evangelical voters in the first-in-the-nation nominating state. There, Cruz warned of a “war on faith in America” and praised “heroes” who had refused service to same-sex couples preparing for their weddings. He also spoke out against Planned Parenthood.

“An innocent life should not be treated as a business transaction,” Cruz told the crowd of more than 2,500. “Selling the body parts of unborn children is a federal crime… If I’m elected president, I will instruct the federal government to open an investigation and prosecute Planned Parenthood.”