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PLANO (AP/CBSDFW.COM) — Six Republican presidential candidates are converging on a megachurch in suburban Dallas on Sunday, underscoring how important the evangelical vote is to many White House hopefuls and the outsized role Texas’ earlier-than-usual primary could play in the 2016 race.

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The event will be live-streamed from 3 p.m. to 7 p.m. on CBSDFW here. CBS11’s Brian New and Jack Fink are tweeting from the scene.

Tea party and home-state favorite Sen. Ted Cruz, retired neurosurgeon Ben Carson, former Arkansas Gov. Mike Huckabee and former Pennsylvania Sen. Rick Santorum were to speak during a 4-hour forum expected to draw 7,000 people to the Prestonwood Baptist Church in Plano. All already enjoy strong support from Christian conservatives.

The church claims nearly 40,000 members over three Dallas-area campuses, and its pastor, Jack Graham, is interviewing all attendees on the importance of faith in their lives.

Former Florida Gov. Jeb Bush and former Hewlett-Packard CEO Carly Fiorina are also to appear. They’d like to boost their appeal to evangelical Republicans. Front-runner Donald Trump isn’t attending.

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A devout Roman Catholic, Bush strengthened his defense-of-life bona fides while governor. He intervened in the case of Terri Schiavo, a brain-damaged Florida woman at the center of a protracted court fight over having her feeding tube removed.

Grassroots groups in tea party-dominated Texas have shunned Bush in favor of insurgent candidates like Cruz or Trump, but Bush has courted Christian conservatives at many events around the country organized by Ralph Reed of the Faith and Freedom Coalition, which also helped put together Sunday’s gathering.

The Plano forum also offers top candidates a chance to make inroads in Texas, the country’s largest conservative state. Officials moved the presidential primary up to March 1, and Texas is now the largest of 13 states voting on “Super Tuesday.”

Former Gov. Rick Perry has already abandoned his short-lived 2016 presidential bid, but Cruz, who lives in Houston, has spent relatively little time in Texas as he campaigns across the country.

Bush was born in the oil-patch town of Midland, and his son George P. Bush was elected Texas land commissioner last year. Bush has done more fundraising than campaigning in the state so far, as has Sen. Rand Paul, who grew up and went to college in Texas.

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(©2015 CBS Local Media, a division of CBS Radio Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)