President Barack Obama moved tentatively today to join the bubbling outrage at the IRS’ targeting of conservative groups, although he said he didn’t have sufficient reason yet to either condemn outright or apologize directly for the tax agency’s behavior.

“If it turns out that IRS employees acted in anything less than a neutral and non-partisan way, then that is outrageous,” Obama said in a mid-morning news conference with visiting British Prime Minister David Cameron.

But he also said he would wait to say more about the revelations — that groups with conservative-sounding names were singled out for heightened IRS scrutiny before being granted tax-exempt status during the 2012 campaign — until Treasury’s inspector general for taxes concludes whether the behavior was politically motivated or otherwise broke regulatory rules.

That yearlong investigation is done and the recommendations are expected to be made public this week, maybe as soon as today.

Since the story broke May 10, congressional anger has come mainly from Republicans, who are falling all over themselves promising all manner of investigations, hearings and legislation. Sen. Marco Rubio, R-Fla., for example, called today for the ouster of the IRS commissioner.

The GOP seems to have had no trouble realizing that it has been handed the gift-wrapped political package of its dreams, a contretemps the public can easily grasp and which will galvanize base supporters behind the two things in Washington they dislike most: the president and the tax collectors.

But congressional Democrats are starting to catch on, realizing that unless they match the GOP in excoriating the behavior of the IRS field office in Cincinnati — which was in charge of reviewing all applications by political groups seeking tax-exempt status — the story will quickly supplant the allegations of a Benghazi attack cover-up, which is both more confusing and has been around for six months, as the most potent Washington controversy of the season.

“The IRS will now be the ones put under additional scrutiny,” said Senate Finance Chairman Max Baucus, D-Mont., who promised a comprehensive investigation by his panel. Sen. Carl Levin, D-Mich., who chairs the Homeland Security and Governmental Affairs Subcommittee on Investigations, has also promised hearings, and statements of outrage were issued this morning by two centrist Senate Democrats, Joe Manchin III of West Virginia and Tim Kaine of Virginia.

The rationale is clear for Democrats getting in as high dudgeon as the Republicans. Their sense of the Nixonian overtones of the facts so far should be as clear as it is to those on the other side, and provide a pretty easy way to score some rhetorical points with the Tea Party crowd.

Democrats may have almost nothing nice to say about what those people believe in, but that has nothing to do with their being out under the IRS’ microscope in ways that haven’t applied to groups with liberal-sounding names. In other words, the Democrats can demagogue the process without getting close to their underlying policies they disdain.

It’s perhaps not so surprising that Obama is taking a more measured approach. It’s still not clear how high up at the IRS the chain of blame properly ascends. And, over the long haul, the agency will need to come up with a non-partisan and easy-to-apply test for the waves of politically committed groups seeking to reap the benefits of the Citizens United decision by registering as tax-exempt “social welfare” organizations.

That process reportedly got started after the Cincinnati office’s first approach was rejected as discriminatory toward groups on the right, but before it came to light. So, in that sense, it looks as though correcting the mistake got started even without the thunderous force of a Washington controversy making it so.