Let’s dispense with this up front: there’s not much chance that Bill Shein will win next week’s Democratic primary for the 1st Congressional District.

But he should.

Shein faces two other candidates in the Sept. 6 primary: Richie Neal, the 2nd District’s congressman since 1989, whose home town, thanks to recent redistricting, is now in the 1st, and Andrea Nuciforo, a former state senator from Pittsfield and now a register of deeds.

As in any race with a long-time incumbent, the challengers have worked hard to convince voters that they offer a better alternative to the status quo—in this case, progressive, for-the-people alternatives to the more conservative, fueled-by-corporate-money Neal. But it’s Shein who makes the most persuasive case, with his focus on economic inequity, the environmental crisis, the damage Big Money has done to our democratic system—the last perhaps the defining issue of his campaign, given that money’s deleterious effect on just about every other issue.

While Neal’s camp is fond of saying he’s backed by firefighters, teachers and “tin knockers,” even a cursory glance at his financial reports make it clear that he’s a candidate of the corporations, political action committees and lobbyists. As of June 30, Neal’s campaign committee and leadership PAC had raised a combined $1.5 million this campaign cycle. The finance, insurance and real estate sectors were, by far, the largest contributing industries, with lobbyists, pharmaceuticals, commercial banks and defense contractors also well represented. Only 24 percent of contributions to Neal’s campaign committee came from individuals; 72 percent came from PACs.

Nuciforo has pointed to Neal’s donor list as evidence that the incumbent is a servant of Wall Street interests. But Nuciforo’s ground is shaky, given his own history of accepting corporate money during his tenure as state senator. And while Nuciforo boasts that his congressional campaign has taken no PAC money, only individual contributions, records show that those individuals include numerous lobbyists, corporate attorneys, and executives from investment firms, mortgage lenders and pharmaceutical companies. (When I asked Nuciforo in a recent interview if he’d refuse all PAC money if he wins the seat, he said he would—”Hold me to it.”)

Then there’s the extremely important issue of Nuciforo’s credibility. Earlier this month, Shein released a statement accusing Nuciforo of plagiarizing large portions of his position papers. Indeed, statements by Nuciforo on women’s rights, the economy, seniors and other issues closely mirrored—at times almost verbatim—statements made by other campaigns, including John Edwards’ 2008 presidential bid and a recent California congressional campaign.

Nuciforo’s response was, frankly, embarrassing: first, he blew off the charges, accusing Shein of playing “desperate” politics; later, his campaign blamed an unnamed former staffer for the apparent plagiarism, before finally accepting “full responsibility”—whatever that means.

There’s plenty in his opponents’ records to make progressive voters flock to Shein, from Nuciforo’s role in killing the voter-supported Clean Elections law as a senator to Neal’s spotty record on reproductive and gay rights. But to describe Shein simply in contrast to his rivals doesn’t do him justice. Shein is a progressive voter’s dream candidate, offering thoughtful, just analyses of what’s wrong with our system, how it got that way and how it can be fixed. (He also writes a very funny press release, which in itself makes him a true political novelty.)

A first-time candidate, Shein lacks a voting record, but he has a personal record, as a political writer and activist, that shows a sincere commitment to progressive causes and reforms. And his campaign has put its money, or lack thereof, where its mouth is, accepting only individual donations of $99 or less—no PAC money, no money from lobbyists or executives whose companies hire lobbyists.

Why, then, am I so pessimistic—some might argue not pessimistic enough—about Shein’s chances next week? Because appealing as he may be to progressive Democrats, they’re simply not the driving force within the party, in Massachusetts or nationally. Time and again, Massachusetts’ Democratic party has proved to be a party that eats its own—particularly its “loony left,” as then-House Speaker, now-convicted felon Tom Finneran infamously described fellow Democrat Scott Harshbarger during the latter’s failed 1998 gubernatorial bid. To other parts of the country, Massachusetts might seem a socialist playground, but on closer inspection, boy, does it have plenty of uninspiring centrist-to-conservative, corporate-serving Democratic pols—and, alas, plenty of voters who are more than happy to keep putting them in office.