The Six Flags Great Adventure theme park in New Jersey is home to the Kingda Ka roller coaster.

According to the park’s website, the coaster ranks as tallest in the world, and fastest in North America, with riders rocketing 456 feet high — that’s 45 stories — and then plunging “vertically into a 270-degree spiral.”

Republicans must feel like they are riding the political version of Kingda Ka when it comes to their party’s candidates for president. The tale has been repeated: A candidate rides up in the polls, and then plunges after wilting in the national spotlight.

Michele Bachmann came out of nowhere, reached the mid-to-upper teens in the polls in mid-June to mid-July. In late November, she had fallen to 4 percent-5 percent. Texas Gov. Rick Perry achieved the greatest heights — nearly hitting 40 percent in late August — but was in single digits in late November polling. Herman Cain went from low single digits in late August to 30 percent in late October. But after assorted accusations of harassment and an affair, Cain’s numbers tumbled.

In recent weeks, it’s been Newt Gingrich rising from the ashes. Gingrich labored in the spring, summer and early fall in single digits. Most assumed Gingrich was done. But by late November, he had taken the lead in the GOP field.

Throughout, Mitt Romney has been steadily in the 20-25 percent range, occasionally peeking slightly above or slipping a bit below. But Romney presents a different kind of thrill ride for Republicans, as he shifted positions on big issues once he was done being governor of liberal Massachusetts and set his sights on winning over conservative Republican presidential primary voters. Romney struggles to break above 25 percent, as Republicans apparently are willing to take a fling on almost anyone else as a potential alternative.

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Of course, Gingrich rates as his own roller coaster ride. He went from conservative backbencher in the House of Representatives to one of the key architects of the Contract with America that helped Republicans gain control of the House in the 1994 election for the first time in 40 years. Gingrich became House speaker. Four years later, after a tough election night, his own party pushed him to resign as speaker.

For good measure, his personal life has been near tabloid worthy, including infidelity charges and now being married to his third wife.

During the current race, Gingrich’s senior campaign staff quit en masse in early June, and with his recent rise in the polls, he’s had to explain accepting big consulting bucks from Freddie Mac — one of the quasi-government agencies responsible for the mortgage and housing mess, and now sucking up taxpayer bailout dollars.

But in some big policy areas, Gingrich has been pretty steady over the years, including being a strong voice for pro-growth tax and regulatory relief.

His campaign tax plan offers six sound steps, for example. First, he pledges to veto any tax increases and “make permanent all current rates of taxation that would otherwise increase automatically in 2013,” which would provide certainty and confidence for investors and businesses.

Second, Gingrich calls for reducing the corporate income tax rate to 12.5 percent from its current 35 percent. That would improve U.S. competitiveness in the global contest to attract business, moving the U.S. from one of the highest corporate tax rates among developed nations to one of the lowest.

Third, Gingrich’s call for eliminating capital gains taxes would serve as a big boost to entrepreneurship and investment, with economic growth, incomes and job creation benefiting accordingly.

Fourth, he wants to abolish the death tax. As noted in his plan, that would allow family-owned businesses to “focus on creating jobs and growing rather than on dealing with tax law.” Tremendous amounts of resources are funneled to lawyers, accountants and insurance companies to avoid estate and inheritance taxes. Those dollars could be used far more efficiently if the death tax were dead.

Fifth, Gingrich wants to permanently let all companies expense capital expenditures made in the year. That is, they would be able to write off 100 percent of spending on investment, such as in plants, equipment and software. That would boost labor productivity, and therefore, worker earnings.

Sixth, the Gingrich tax plan calls for the option of a 15 percent flat tax. Taxpayers would be able to pay under the current system or under a 15 percent flat tax with a $12,000 personal deduction for each person, and deductions for charity and home ownership.

From the perspectives of economic, business and employment growth, that’s an excellent tax agenda. No doubt, it appeals to Republican primary voters.

But those same voters, again as illustrated by the polls, seem to be longing for a presidential candidate who is solid and steady on both character issues and policy issues, especially in an election where the incumbent is so clearly vulnerable. But it does not look like across-the-board “solid and steady” is going to happen for Republicans this year. Instead, it could be a continuing roller coaster ride up to November 2012.

Of course, that means uncertainty and stomach troubles not just for Republicans, but also for businesses and the economy in general. Let’s call it the Kingda Ka election.

Raymond J. Keating is the chief economist for the Small Business & Entrepreneurship Council. His new book is “Chuck” vs. the Business World: Business Tips on TV.