The Republican-supporting nonprofit Crossroads GPS is out with a new ad attacking President Obama over the collapse of Solyndra.

The $500,000 week-long buy on national cable is the conservative group’s second attack focused on the badly bungled stimulus investment in the solar energy company.

“$500 million to Solyndra now bankrupt,” the narrator says. “Laid-off workers? Forgotten. Typical Washington.” The ad quotes a Washington Post story calling the White House handling of the green-technology program “infused with politics at every level.”

For a national ad, it’s a small buy (combined with its super PAC arm, American Crossroads, Crossroads GPS raised $51 million in 2011). But it’s also revealing. Eight months from the election, Solyndra appears to become the prime attack against Obama — and the one he is most keen to blunt.

Americans For Prosperity, the conservative group founded by the billionaire Koch brothers, spent $6 million in swing states on its own ad attacking Obama on Solyndra.

Obama’s first campaign ad defended him against these attacks, saying “secretive oil billionaires attacking President Obama with ads fact-checkers say are not tethered to facts,” citing an ABC News analysis and noting that the clean-energy industry had created 2.7 million jobs.

Obama also promised to “double down on [the] clean energy industry” in his State of the Union. “Some technologies don’t pan out; some companies fail. But I will not walk away from the promise of clean energy,” he said.

It’s not hard to see why conservatives have seized on Solyndra — it’s an example of stimulus funds poorly spent, government meddling in private enterprise, and political concerns seeping into policy decisions all in one neat package.

Is it a good strategy for Obama to engage? As The Fix wrote when Obama’s ad aired, it’s hard to imagine positive push back resonating much. And the more he talks about Solyndra, the more fuel he gives to his critics.