– Finally, they had the debate stage to themselves: The philosopher-politician vs. the businessman-preacher.

And for 90 minutes on Saturday night, there were no rehearsed attacks. Gone were the shiny podiums and 30-second rebuttals. In were the armchairs and three-minute monologues.

Newt Gingrich, the onetime House speaker whose appeal is his endless buffet of ideas, and Herman Cain, the former restaurant executive whose appeal is his folksy simplicity, faced off Saturday night in the friendliest of presidential debates.

They expounded upon their prescriptions to overhaul Medicare, privatize Social Security and rein in federal spending. Gingrich and Cain offered a dramatically different vision for government from that of the current occupant of the White House. But between the two Republican presidential hopefuls, there was hardly any daylight.

“We both represent a willingness to talk about common sense without regard to whatever the national establishment thinks is acceptable,” Gingrich said. “We are by any reasonable standard the two most radical candidates in this because we both are willing to say common sense — and in the city of Washington, common sense is such a radical idea.”

 The candidates sat side by side at a table and unleashed their intellectual and rhetorical firepower on a ballroom of several hundred tea party activists in this Houston suburb. Modeled after the Lincoln-Douglas debates of 1858, the Gingrich-Cain debate was designed to signal a departure from the it’s-my-turn-to-speak gotcha slugfests that have dominated the GOP presidential debate circuit.

“Since it’s the two of us, we can change the rules as we go,” Cain quipped.

The event, a tea party fundraiser organized by the Texas Patriots Political Action Committee, with tickets costing $150 to $1,000, was hotly anticipated. After surging in the polls, Cain struggled over the past week to steady his campaign amid reports that two female subordinates of his at the National Restaurant Association once filed official sexual harassment complaints against him. But, at the request of debate organizers, the allegations were not addressed during Saturday’s forum.

On the one subject where Gingrich and Cain have publicly disagreed — over Cain’s signature tax plan that would institute a 9 percent federal sales tax, which Gingrich does not favor — the two did not argue.

“You first have to convert the tax code to a 9-9-9 plan. I’m about fixing the problem,” Cain thundered to hearty applause.

Moments later, Gingrich said: “I’m going to sidestep the temptation to talk about 9-9-9.”

Instead, he saved his swipes for President Obama.

“This president is about as candid and truthful as Bernie Madoff in what he tells the American people,” Gingrich said in reference to the financier convicted of a Ponzi scheme.

If any two Republican candidates may be brothers from different mothers, as Cain referred to his relationship with the wealthy Koch brothers, they are Gingrich and Cain. They first locked arms in the mid-1990s over their mutual abhorrence of health-care reform and support for welfare reform.

But there can be only one Republican nominee, and Gingrich and Cain stand in each other’s way. Both Georgians are vying to emerge as the conservative grass-roots alternative to the party establishment front-runner, former Massachusetts governor Mitt Romney, and ultimately do what both men most relish: take the fight to Obama.

Cain is almost even with Romney at the top of the field of GOP candidates, 23 percent to 24 percent, according to the most recent Washington Post-ABC News poll. Gingrich is behind, but at 12 percent is in double digits for the first time, running neck-and-neck for third place with Texas Gov. Rick Perry at 13 percent.

Onstage Saturday, Gingrich seized the opportunity to show off his mastery of policy matters. He spoke with ease about the intricacies of health policy, saying the nation’s health system should be less bureaucratic and more consumer-friendly.

“Think about going to McDonald’s,” Gingrich said. “We have no national hearings on fraud at McDonald’s. You show up and say, ‘I’d like a Quarter Pounder with Cheese.’ You give them money. They are happy. You are happy. If you open up your bag and there’s no Quarter Pounder with Cheese, you are unhappy.”

When Cain was asked about a private alternative to Medicare, he seemed stumped.

“You go first, Newt,” he said.

“It’s only fair,” Gingrich responded, before offering his opinion.

Many party leaders are skeptical that either Gingrich or Cain can go the distance, especially when compared with Romney and Perry, who are judged to be running far more serious campaigns. Where Romney and Perry are campaigning the traditional way — raising money, building ground organizations, stumping across the early voting states — critics say Gingrich and Cain are leveraging the notoriety their candidacies provide to sell books (and, in Gingrich’s case, films).

 But Gingrich and Cain say they are trying to prove that one can win without tearing the other guy down. They assert that the nominating contest should not be a series of schoolyard quarrels over immigrant lawn workers and college tuition breaks, as at previous GOP debates, but rather a battle of big ideas.

 “It’s so smart,” Republican pollster and strategist Frank Luntz said. “Gingrich will demonstrate why he’s brilliant, and Cain will demonstrate why he’s likable. And they won’t try to score points off each other. They will score points off the president, which is what Republicans want them to do anyway.”

Tom Perdue, a Republican strategist in Georgia, said Gingrich and Cain have “nothing to lose.”

“They don’t jump into screaming over somebody, screaming at somebody,” Perdue said. “They both try to talk to the audience — the audience being America — and they’re both good with a quip, with a sound bite. So why would they not do this? While Romney is the front-runner, there’s still a desire among Republicans for somebody other than Romney.”

 Both men want to be that somebody. But their competing ambitions don’t seem to tarnish their friendship.

 “They’re not traditional politicians,” Luntz said. “Newt is a lover of ideas, and Cain is a lover of life.”

In Washington more than a decade ago, Cain and Gingrich became political allies. Gingrich was the new House speaker, leading the Republican revolution against the Democratic policies of President Bill Clinton. Cain was the charismatic president of the National Restaurant Association, a trade group he transformed into a powerhouse in the halls of Congress.

Cain, a former chief executive of Godfather’s Pizza, had become a minor celebrity in conservative circles when, in 1994, he challenged Clinton on national television during a town hall meeting on health care. Cain declared that Clinton’s calculations were “incorrect,” saying his health-care plan would force small businesses to cut jobs.

Gingrich and other Republican congressional leaders saw promise in Cain, appointing him to a national tax reform commission. led by former Housing and Urban Development secretary Jack Kemp.

Cain became part of Gingrich’s “corporate kitchen cabinet” and lobbied him on industry-friendly policies such as fighting restaurant smoking bans and minimum-wage increases.

 Gingrich and Cain pushed aggressively for welfare reform. In January 1995, during his first month as speaker, Gingrich appeared at a news conference with Cain to hail the restaurant industry’s pledge to hire and train welfare recipients.

Cain said such work is often dismissed as “low-wage, dead-end, hamburger-flipping, pizza-swinging jobs,” but he hailed himself as an example of how a dishwasher can become the boss.

Then Cain introduced Ed Treacy, who started at Domino’s delivering pizza and by his mid-20s was running Washington’s top-selling Domino’s outlet. For this, Gingrich was full of praise.

“When Herman Cain can come to Washington and say the word ‘Domino’s,’ we are clearly on the road to reconciliation,” Gingrich said, according to an account in the Omaha World-Herald.

Now, 16 years later, Gingrich and Cain are competing for the same prize. But as they stepped out for Saturday’s debate, they were more partners than opponents. They put their arms around each other, waved and grinned.

Then the two said they’d like to see both of their names on next year’s Republican ticket. They just disagreed about whose name would be on top.

Washington Post polling director Jon Cohen contributed to this report.