Former U.S. Rep. Tim Penny, who represented southern Minnesota's First Congressional District in the 1980s and '90s, once shared some cynical advice he'd received from a hard-boiled veteran in Congress. Whenever a politician has to choose between "the interests" and "the people," went the idea, it's best to side with the interests.

The people forget. The interests remember.

There's sobering (but as we'll discuss, not entirely unwholesome) truth in this about America's political marketplace. And it's a truth whose complexities now confront the current congressman from Minnesota's First District — U.S. Rep. Tim Walz — as he adjusts his posture and rhetoric on the gun-control issue.

Walz is running to be the DFL candidate for governor. The gun issue, which has periodically surged and receded in emotional intensity over many decades, is surging, as powerfully as ever, in the wake of what we amazingly must call America's "latest" shattering mass shooting.

And for Walz, as a self-styled centrist Democrat, the political landscape ahead is treacherous.

The moderate position on gun issues is one thing in the largely rural First District. But the center is found in a radically different place among progressive DFLers who will dominate the contest for the party's nomination.

And should Walz face a statewide general electorate in November, needing to run up his party's usual big margins in the ever-more-liberal Twin Cities core while holding his own outstate — it won't be simple to again recalibrate his balance on guns (especially if the debate's intensity lasts).

All this explains why Walz used this space in last week's Star Tribune to explain that he has long supported reasonable gun-control measures, is evolving to favor even more, and no longer has much good to say about the NRA, although he remains a proud, respectful native of America's ethical-gun-owning culture.

It's not exactly a full-throated battle cry — but it's about where the center may be just now.

Walz's discomfort illuminates America's challenge in finding enough common ground to at least attempt to reduce our country's uncivilized level of gun violence.

It's important to pause here and acknowledge that, overall, rates of violence are sharply down in this country over the past several decades — good news that is too little discussed. But no society can passively tolerate lunatic mass murders becoming almost routine.

The main obstacle to measured gun law reform in America is the advantage an "interest" often has over "the people." But this doesn't mean only, or even mainly, special interest organizations like, in this case, the NRA, which certainly plays its part throwing around its money and its weight. Ultimately, the real "weight" on this issue comes from a critical mass of American gun owners who care adamantly about their gun rights and are prepared to take political action to defend them.

The outsized clout of single-issue passions is nothing new. But we've seen striking examples in recent years, often on the left, of how small, dedicated constituencies — "interest groups" in a less-sinister sense — can achieve surprising political victories, especially on issues cast as liberation causes, even when public opinion is solidly against them at the outset. Think of gay rights, same-sex marriage, the still developing transgender agenda, legalized marijuana, the $15 minimum wage, etc.

Gun rights are a Red America liberation movement. And a point worth pondering is that the success of all these interest-group movements shows that in our political system it is often not the biggest constituency that prevails but the one that cares the most about an issue. In principle, that's not the worst way to settle differences.

It is often incredulously asked in progressive circles how "common-sense gun control" can fail to be enacted when big majorities of Americans tell opinion polls they support tighter background checks, bans on assault rifles and/or large ammunition magazines, etc., etc.

The probable answer is that politicians have concluded it takes little commitment to answer a poll question, while core gun-rights defenders constitute a true "interest" not to be toyed with. A not insignificant number of people will get out and vote — who otherwise might not — to support an outspoken gun-rights advocate or defeat an outspoken gun controller. Some will even jump party lines in a particular race to back gun rights, when on most other issues they lean the other way.

The question this late winter, of course, is whether a "tipping point" of outrage has been reached that will turn a decisive number of philosophical gun-control supporters into more of a lasting, action-taking "interest" — perhaps by bringing out more young voters motivated on the issue.

We shall see. But the political battle ahead could be prolonged should two militant gun-issue interests materialize. (The abortion issue comes to mind.)

Action might come sooner if some elusive, Walzian middle ground actually could be found.

One key would be if "common-sense" gun law reformers could convince more moderate-minded gun owners (who also frequently tell pollsters that they support broader background checks, ammunition limits and so on) that the gun-control movement would be satisfied with measured "common-sense" steps — that these are not just preliminary moves in a crusade to largely outlaw private firearm ownership.

And a step in that direction could be taken in the debate Americans are having right now — and in fact, Gov. Mark Dayton showed how last week when he declared himself, at least for now, open to all ideas for making schools safer. It would help if more of those clamoring to better protect school kids could at least discuss more constructively and with less instant derision the idea of enhanced armed security at schools — even if not "arming teachers" exactly.

All such proposals pose difficulties, no doubt. But some openness to at least exploring approaches to greater safety that resonates for those who see guns not merely as destructive but also as protective in the right hands might open communication.

Just last summer — only several shocking shootings ago — a considerable number of politicians almost certainly had their lives saved because armed security happened to be on hand when a gunman opened fire at a congressional baseball practice. Worth remembering, perhaps, in the debates ahead.

D.J. Tice is at Doug.Tice@startribune.com.