The GOP 2012 presidential nomination contest so far has centered almost exclusively on economic issues: the major candidates blasting President Obama for increasing the federal budget deficit and criticizing one another’s records on health care and job creation.

Texas Gov. Rick Perry (R), who is expected to announce his presidential candidacy in the next few weeks, will start to change that on Saturday, by hosting a day of prayer and fasting in Houston dubbed “The Response.”

Attendees from Texas and across the country will gather at a pro football stadium to ask for “God’s forgiveness, his wisdom and his provision for our state and nation,” according to Perry’s video invitation.

The event, originally conceived by Perry before he started laying groundwork for a presidential campaign, is one of the most explicit appeals to conservative Christians by any of the Republican hopefuls, and it will closely link his candidacy to his evangelical faith if he decides to run.

Evangelical Christians make up a critical voting bloc that could comprise more than half of the voters in some of the GOP primaries. But liberals are criticizing Perry, highlighting the controversial comments of some of the people he has invited to participate. And some Republicans worry that the Texas governor could hurt his prospects of winning the general election if he chooses to emphasize religion rather than his record of job creation.

The event “might play well in Iowa or South Carolina, but I’m not sure how well it plays in New Hampshire, Florida or Michigan. It’s too much of an overt mixing of religion and politics,” said John Feehery, a Republican strategist who was a top adviser to J. Dennis Hastert (Ill.) when he was the House speaker. “Rick Perry has got to decide if he wants to run for president or run to replace Pat Robertson.”

More than 8,000 people have signed up to attend “The Response,” according to its organizers — a turnout that would be larger than any event the other Republican candidates have held this year.

Perry invited his fellow governors to the event, but so far, only Kansas Republican Sam Brownback has said he will come.

From 10 a.m to 5 p.m., attendees are expected to pray, abstain from eating and listen to a series of speakers at Reliant Stadium. Organizers said Friday that Perry will address the crowd, as will major Christian conservative figures such as Richard Land of the Southern Baptist Convention, Tony Perkins of the Family Research Council and James Dobson of Focus on the Family.

Perry says the day is inspired by the words of the Old Testament book of Joel, in which the prophet calls on the Hebrew people to pray, fast and ask for God’s forgiveness. The Texas governor argues that America similarly needs to ask for God’s help today because it is a “nation in crisis.”

“We have been besieged by financial debt, terrorism, and a multitude of natural disasters,” Perry writes on the event’s Web site. “As a nation, we must come together and call upon Jesus to guide us through unprecedented struggles, and thank Him for the blessings of freedom we so richly enjoy.”

Officially, the event is non­political. Perry does not have a formal presidential campaign staff, and the American Family Association is paying for the rental of the 71,000-seat stadium.

Organizers don’t detail positions on any major policy issues on the event Web site; instead, they list seven religious points they agreed on, such as “We believe the Bible to be the inspired, the only infallible, authoritative Word of God.”

Some of the groups and figures involved are highly controversial. Following the Fort Hood shootings two years ago, a top official at the American Family Association, Bryan Fischer, said Muslims should be not allowed to serve in the U.S. military. He has also suggested Adolf Hitler and the German soldiers who carried out the Holocaust were gay, and their sexual orientation was part of the reason they orchestrated the mass killings.

A Texas pastor named John Hagee, who is listed on the event’s Web site, has suggested Hitler and the Holocaust were part of God’s plan to drive Jews from Europe.

The Texas branch of the American Civil Liberties Union and a group called Americans United for Separation of Church and State planned to hold can change once it startsan event Friday night in Houston to protest “The Response.”

“Governor Perry’s decision to sponsor a ‘Christians-only’ prayer rally is bad enough,” said the Rev. Barry W. Lynn, executive director of Americans United. “That he turned to an array of intolerant religious extremists to put it on for him is even worse.”

Since 2008, the Republican Party has shifted its focus somewhat away from debating moral values. On the eve of last year’s elections, top GOP leaders largely avoided inserting moral or social issues into their “Pledge to America” policy document, focusing instead on the economy and health care.

Some Republican strategists privately say that highlighting the party’s opposition to gay marriage in particular turns off young and swing voters. They say Perry can avoid annoying these voters if the event remains largely about prayer instead of crossing into those sorts of issues.

“The only possible risk with the event is if one of the other participants says something that Perry has to disavow,” said Dan Schnur, a former adviser to Sen. John McCain (R-Ariz.). “But as long as the tone is inclusive rather than exclusive, this is a smart way for him to solidify his social conservative credentials before formally getting into the race.”

David Carney, Perry’s top political adviser, said that economic issues will be the biggest focus in next year’s election, but he argued that voters would not punish a candidate for talking about his religion.

“I think those who would try to use a person’s faith or lack of faith as a political weapon will not find a very receptive audience outside of the salons of the elite in our nation,” he said in an e-mail message.

Perry is not the only candidate in the 2012 field speaking about faith and moral values. Rep. Michele Bachmann (R-Minn.) has addressed congregations in Iowa, and former Minnesota governor Tim Pawlenty (R) released a long video detailing his religious views. But these candidates and others have also largely stuck to economic themes in debates and other forums with wider reach. None has held any event that approaches “The Response.”

On the Democratic side, President Obama has met with religious leaders throughout his tenure, and his reelection campaign is expected to again try to win evangelicals, particularly those under age 40 who are less tied to the Republican Party.

Perry was raised in the Methodist Church, but he now attends a nondenominational megachurch in Austin. As he has flirted with a presidential run, some influential tea party activists, evangelicals and economic conservatives have said they would back him, giving him the potential for a candidacy that would unite the GOP.

“I think a lot of evangelicals feel very positive about Rick Perry,” said Warren Smith, associate publisher at World Magazine, a Christian biweekly. “He’s got an economic story to tell that will tap into the ‘It’s the economy, stupid’ theme, but he’s also got a real story to tell when it comes to social issues, and this event is a real example of that. It’s possible that this could make him the candidate of evangelicals.”

Staff writer Philip Rucker contributed to this report.