Just a few days before the Michigan primary, a private equity trade group has released a video celebrating the impact of a $850 million investment by the Blackstone Group in the Detroit Medical Center. The group says the investment created 15,000 construction jobs and a children’s hospital, among other politically salient accomplishments:

It’s all part of the Private Equity Growth Capital Council’s campaign to rehabilitate the industry’s public image — an effort launched a few weeks ago after the attacks on Romney’s tenure at Bain Capital.

The trade group, however, says it’s not specifically aiming to bolster Romney’s prospects in Michigan on Tuesday. “This campaign is not about a single candidate nor a political party,” PEGCC spokesman Ken Spain told National Journal’s Chris Frates. “[W]e plan to inform and educate...while setting the record straight in advance of the political mischaracterizations and attacks on the industry that will likely come.”

In fact, the Blackstone Group is currently under fire for cutting jobs in upstate New York as part of its takeover of a food company. And a bigger political battle over private equity has already opened up on another front: President Obama’s new corporate tax overhaul would eliminate an tax exemption for private equity firms, spurring the industry to go on the defensive yet again.