When Texas Gov. Rick Perry formally launches his presidential bid Saturday, his candidacy is expected to shake up the GOP field and give the White House pause.

That’s because Perry is seen as the one candidate who can appeal to social conservatives, Tea Party activists and establishment Republicans.

He is credible on issues social conservatives care about and sent a strong message to evangelicals last weekend by hosting a national prayer rally in Houston that drew roughly 30,000 Christians. He also has overseen a period of job growth in his state, making Texas one of the few states in the country to have posted economic gains.

President Obama’s political team, which until now had mostly focused on attacking the front-runner Mitt Romney, gave Perry a “Welcome to the NFL” hit on Friday.

David Axelrod, a senior adviser to Obama, reminded CBS News that Perry once called for secession from the United States and refused to give Perry credit for the Texas economy.

“He’s been the beneficiary down there of the boom in oil prices, and obviously a state like Texas is going to benefit from that -- and increased military spending because of the wars, because Texas is home to many military bases,” Axelrod said. “I don’t think many people would attribute it to the leadership of the governor down there.”

Other Republican presidential candidates who may have to crank up their campaigns to keep pace with Perry, were much kinder when asked about his expected candidacy during Thursday's debate in Iowa.

Texas Rep. Ron Paul said he was "pleased" Perry was joining the field "because he represents the status quo." Businessman Herman Cain called Perry "one more politician."

Former Utah Gov. Jon Huntsman joked that "we all need prayers" and said he hoped Perry was praying for the GOP field.

In fact, Perry, a devout Christian whose faith defines his politics, will likely compete with Rep. Michele Bachmann for the support of evangelical Christians.

Bachmann who has long tied her political beliefs to her faith, won't discuss how Perry's entry into the race affects her strategy. But on the eve of the Texas prayer rally, her team sent reporters a roster of supporters, including more than 100 pastors and spiritual leaders in Iowa.

"For that group of voters, they will be battling it out," said David Roederer, who held top Iowa posts in John McCain's 2008 campaign and George W. Bush's 2000 bid.

Perry will also be competing with former Pennsylvania Sen. Rick Santorum and former Minnesota Gov. Tim Pawlenty for votes among faith-driven voters.

But the candidate who should probably be most worried is Romney, whose front-runner status will likely face its stiffest challenge yet.

In polls conducted before he joined the race, Perry was in a statistical tie with Bachmann in the runner-up slot and within striking distance of Romney.

Perry, who has been governor for 11 years, has touted his business-friendly job-creation skills in Texas as evidence of fiscal wisdom, giving him a chance to drain support from Romney, whose conservative record is burdened by the health care plan he implemented as governor of Massachusetts.

And Iowa, with its strong base of evangelical voters, may be tailor-made for Perry. He was making his first trip to the state Sunday, a day after formally announcing his candidacy in South Carolina and New Hampshire -- just as Iowa straw poll votes are being cast.

A caucus campaign by the Texan could force Romney to retool his strategy of downplaying the state -- which he lost during his first run in 2008 after investing heavily -- in favor of friendlier ground elsewhere.

"Perry hasn't shown up in the rodeo yet, but it looks like a Romney-Perry race," Republican strategist Jim Dyke said.

The Associated Press contributed to this report.