A letter sent from the Treasury Inspector General to Representative Sandy Levin of Michigan will certainly undermine the argument that progressive organizations were subject to the same undue scrutiny as Tea Party groups. And that's too bad, because the IRS scandal, such as it is, has become a tar pit of futility, an endless game of darts in which the winner is the first to score infinity points.

To describe why this is important, some background is necessary.

Everyone in Washington, D.C., agrees that the IRS' tax-exempt division should not have singled out groups with the words "Tea Party" in their names for special scrutiny when considering their applications. Everyone. Everyone on Capitol Hill, at the White House, at the IRS. This happened from the outset, in fact, when Congressional Republicans blasted the findings in a report from the Inspector General, J. Russell George, and their Democratic colleagues quickly joined in. The new head of the IRS, Danny Werfel, repeatedly criticized the agency's behavior.

That unanimity left little room for political posturing, so the debate became about minutiae. Rep. Darrell Issa and his Democratic colleague on the House Oversight Committee, Rep. Elijah Cummings of Maryland, started scrapping over transcripts of interviews with agents involved in the targeting. Issa's goal was to stretch a line from the agents to Obama; Cummings' was to put the whole thing to bed. Neither effort worked.

On Monday, Congressional Democrats scored a coup. The group obtained documents from the IRS including "Be On the Look Out" (BOLO) lists, lists of terms or issues found in applications meant to give auditors in the tax-exempt division guidelines for additional scrutiny. Included among the terms was the word "progressives."

The instant and natural reaction was to assume that the push to insinuate unproven bias by the Obama administration was dead. We ourselves made that case. After all, if progressives were on BOLO lists, it seems unlikely that the president — either directly or through some sort of secret code — had asked that they be included.

Rep. Levin, the ranking member on the House Ways and Means Committee, demanded to know how much scrutiny those progressive groups got. On Thursday morning, he asked the committee's chair, Rep. Dave Camp, to bring IG George back to testify about the inclusion of "progressives." While Cummings had failed to drive the IRS scandal into a cleanly dug grave, Levin thought he might have a better chance at the wheel. Until George pre-empted him with a letter. (The entire thing is at the end of this article.)

From our audit work, we did not find evidence that the criteria you identified, labeled "Progressives," were used by the IRS to select potential political cases during the 2010 to 2012 timeframe we audited. The "Progressives" criteria appeared on a section of the "Be On the Look Out" (BOLO) spreadsheet labeled "Historical," and, unlike other BOLO entries, did not include instructions on how to refer cases that met the criteria.

In other words: the term "progressives" didn't result in the same sort of scrutiny that "Tea Party" did, nor did it happen in the same time period. And yes, George continued, there were progressive groups that were slow-walked by the tax-exempt group during the same period as those Tea Party groups. But:

In total, 30 percent of the organizations we identified with the words "progress" or "progressive" in their names were processed as potential political cases. In comparison, our audit found that 100 percent of the tax-exempt applications with Tea Party, Patriots, or 9/12 in their names were processed as potential political cases during the timeframe of our audit.

And so the IRS scandal skips past another derailment. "Progressives" was a different category of term, according to the man who did the analysis that brought the scandal to life. Just as when Cummings pointed to the origination of the Tea Party targeting as being form a self-described "conservative Republican," the effort to make the IRS' action into an indictment of the president can move forward.

Or, more accurately, it can remain where it is, stuck in the mud of Capitol Hill. Perhaps one side or the other will prove its case — the Republicans that it's Obama's fault, the Democrats that it's a non-issue. But it's more likely that neither case is provable, and so the IRS scandal will just sit where it is forever, while arrows fly over its head.