In America at least, political parties exist to operate as grand coalitions, bringing together diverse interests in pursuit of broadly shared goals within a republican framework of separated powers.

In Europe, on the other hand, parties tend to be more pure. That’s why there are so many parties in European democracies, and why those governments have become increasingly dysfunctional.

The late Paul M. Weyrich, no conservative slouch but nonetheless a man interested in seeing conservatives govern after generations in the policy wilderness, told me a funny story early in my 10 years of work with him during the 1980s.

We were discussing the tendency in politics among kindred spirits to emphasize subtle policy differences rather than unifying principles. Paul’s tale was set in the “Old Right” days of the 1960s.

Two hard-core conservatives are having their customary Friday evening drinks at a D.C. watering hole. They decried the latest failure of fellow conservatives in Congress to stop this or that advance of Lyndon Johnson’s “Great Society” program, certain to bring debt and social turmoil to the nation.

After cataloguing the sins of every voting leader in both the House and Senate, the older of the two gentlemen said to his somewhat younger colleague: “You know, there are only two true conservatives left in Washington, and that’s me and you.”

Pausing for effect, he stares at his friend and adds, half-joking: “And I’m not so sure about you.”

I am reminded of a faction of conservatives who once grew frustrated with conservative state Rep. Leonard Sullivan. The charge of “RINO” (Republican In Name Only) was laid at Sullivan’s feet. Many conservatives took seriously the proposition that Sullivan—the guy who held University of Oklahoma law school leadership accountable for empowering Anita Hill when she went after Clarence Thomas in 1991—was a RINO.

Most recently, we see this tendency in divisions nearing resolution in the June 24 Republican primary for the U.S. Senate seat that Tom Coburn will vacate at year’s end.

Some conservatives prefer U.S. Rep. James Lankford, R-Oklahoma City. (Lankford is not a “RINO,” and when he is tagged as such the term has lost its meaning.) Other conservatives believe former Oklahoma House Speaker T.W. Shannon, R-Lawton, is the best choice. And one can make a case for Randy Brogdon, the former state senator in the U.S. Senate race, who ran impressively against Mary Fallin in the 2010 gubernatorial campaign but who will probably finish third in the federal race this year.

It is easy to sympathize as each of the candidates makes a case against the others. Adding to confusion, rather than clarity, is the at times overwhelming sequence of advertisements from national independent groups, stressing the saintliness of their preferred candidate while decrying the sins of the other(s).

To be sure, voters have to choose how to lift up conservative principles. In the end, the decision for voters is who among these three will best advance the conservative agenda. Who will best uplift the conservative cause of limited government and personal liberty?

Primary voters are grappling not with fundamental differences, but shades of difference—nuances among fellows who vote the “right” way 90 percent of the time or more.

The Republican tendency to emphasize differences rather than similarities came to mind as I observed its mirror image, in the collapse of leadership prospects for a Democrat I respect, state Sen. John Sparks of Norman.

This spring, he was on track to become the Democratic leader in the state Senate, replacing Sen. Sean Burrage, D-Claremore.

Those of us in the Capitol press corps frequently interacted with Burrage and Sparks these past few years, in stand-up interviews in the hallways or in cordial but sometimes contentious interviews in Burrage’s office.

Sparks gave as good as we reporters gave, shooting back at questions from me or others as he made pointed criticisms of one or another decision of the Republican Senate majority. No shrinking violet, he assailed GOP priorities on issues as varied as taxation, spending, education, and government employee pay.

Still, his jabs were usually thoughtful and issues-driven, not purely partisan.

When Sen. Sparks was named minority leader-designate in February, he proudly declared, “The Democratic Caucus provides contrast where it is needed: we ask the hard questions; we shine light on the dark spaces; and we hold the Republicans accountable. I look forward to working with my fellow Democrats as we continue our efforts to create opportunity and promise for hard-working Oklahomans and their families.”

Burrage hailed his longtime friend as “a loyal, hard-working, and effective lawmaker.” Gov. Mary Fallin praised Sparks, saying, “Republicans and Democrats alike want to make Oklahoma a stronger, more prosperous state for our citizens to live, work, and raise a family.” It was hard to disagree with any of that.

Then, in March, came rising tensions around the important debate over energy policy and taxation of drilling activity.

In a newspaper essay, Sparks laid out his position on drilling taxes, writing, “It’s bewildering that some of Oklahoma’s most high-profile elected officials are trying to raise taxes on oil and gas under the pretense that the industry needs to pay its fair share.”

Once upon a time, the tax on oil and natural gas wells was 7 percent at the well-head. Then came the Great Recession and accompanying challenges for what is sometimes called, in the Okie vernacular, “the oil and gas bidness.”

The Legislature of that era, working with Democratic Gov. Brad Henry, fashioned an incentive for then-experimental horizontal drilling technology, dropping the rate to just 1 percent for the first 48 months of activity. The rate for horizontal wells then returns to the rate for all other wells, the traditional 7 percent.

The debate that heated up in March and continued through April and May was whether to let the rate go back to 7 percent or somewhere in between. Some like keeping it at 1 percent, which has fed an historic boom in drilling; many in the industry want to raise it to 2 percent; and a few say the rate could be as high as 5.3 percent. In that debate, the Oklahoma Council of Public Affairs (OCPA) was sympathetic to the lower rate or rates; the Oklahoma Policy Institute pressed for the higher rate or rates.

It’s an argument, so there’s been a lot of debate.

Sparks, the loyal, hard-working, and effective Democrat, laid out a position closer to most voices in the industry than to tax consumers or their allies.

The case for a higher rate was made in arguments that the incentive “cost” the state $161 million last year, and that would rise to $251 million this year. The opposite argument was made from the industry side, with independent producers pointing out the energy business is paying more than $800 million in gross production taxes every year, and accounting for 25 percent of all taxes paid in Oklahoma.

Senate Democrats threw Sparks overboard. They replaced him with state Sen. Randy Bass of Lawton. While giving a tip of the hat to the oil and gas business, Bass said “we also understand the serious needs facing our state, particularly in education.”

The Senate Ds were apparently upset that Sparks had made himself a player in energy tax negotiations, rather than letting “those discussions unfold before staking out a definitive position.” So, Bass said, they decided “we needed to go in a different direction to move the caucus forward.”

Let’s be honest. The decision that was made was to remove from party leadership a guy whose advocacy of the energy business put him square in the tradition of former U.S. Sen. Robert S. Kerr, former U.S. House Speaker Carl Albert, and former Gov. Brad Henry.

At the risk of stating the obvious, this is an odd way to advance the interests of a caucus that presently has 12 members, in a chamber of 48.

Patrick McGuigan (M.A. in history, Oklahoma State University) is editor of CapitolBeatOK.com. He is the editor of seven books on legal policy, and the author or co-author of three books, including Ninth Justice: The Fight for Bork. Last year the Washington Post political blog, “The Fix,” designated McGuigan one of the three best political reporters in Oklahoma.