The dire warnings contrast directly with the sunny optimism his top rivals often exude.
GOP front-runner Mitt Romney talks about how much he loves America. And Newt Gingrich lectures on the nation's unique place in the world and its potential to free the world.
They are following legions of other politicians who have used optimism to court voters with visions of the country's greatness.
Ronald Reagan ousted Jimmy Carter in 1980 by asking whether Americans wanted a chance for a better tomorrow. Four years later, Reagan won with his rhetoric about America as a "shining city on a hill," a notion borrowed from a 17th-century Puritan. Bill Clinton captured the presidency by appealing to voters' middle-class struggles and urging them "don't stop thinking about tomorrow."
George W. Bush captured the White House in 2000 with the promise to restore dignity to the office after the scandal-ridden Clinton years. And Obama won his first term in the White House on a message of hope and change, appealing to voters' desire to turn the page after eight years of Bush.
At times, Santorum seems to be doing the exact opposite, currying favor with voters by appealing to their frustrations with Washington as he looks to regain his own political footing after three consecutive losses in the GOP nomination race.
"Every once in a while Rick may get passionate and come across as angry, but Americans can appreciate that, because a lot of people out there are angry at where we are right now and they're looking for a fighter who understands their struggle," Santorum spokesman Hogan Gidley said.
The former senator pitches himself as the only politician standing between a wholesale meltdown of American values and a political tsunami for his GOP.
On the health care overhaul, Santorum warns: "Be careful what you do ... because once the government creates a right, it can tell you how to exercise that right."
On Obama's regulations, he says: `Under Obamacare, you are going to have to provide insurance coverage, free coverage, for things that are absolutely against the teaching of the Catholic Church: free sterilization, free abortions. ... This is just the tip of the iceberg of what we can expect."
On Iranian policy, he warns that Tehran first would destroy Israel and then turn its sights on the United States. "They cannot have a nuclear weapon, because you, in Greenville, will not be safe," he said in South Carolina.
And on declining marriage rates, he adds: "Taxes go up and the economy struggles. We know that marriage and the two-parent family is the unit upon which this country was founded."
Santorum also constantly warns that neither Romney nor Gingrich would be an effective challenger to Obama and says he's sounding the alarm against a political disaster.
"Barack Obama, in a debate or in this election, is going to destroy Mitt Romney on the issue of health care," Santorum told a crowd in Woodland Park.
As for Gingrich, he says this of the former House speaker: "Way too erratic."
(Copyright 2012 by The Associated Press. All Rights Reserved.)