FREMONT (CBS SF) — Mitt Romney made an unannounced visit to bankrupt solar company Solyndra Thursday to make the case against President Obama’s economic and green energy policies.

The Republican presidential candidate held a news conference outside the shuttered headquarters in Fremont with his campaign going to great lengths to conceal the plans.

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Once the poster company for Obama’s economic stimulus program, the vacant Solyndra plant shows how little the President understands free enterprise, Romney said.

The presumed Republican presidential nominee defended his own record in private equity and suggested the Solyndra deal smacked of cronyism, charging that Obama campaign contributors stood to gain if the government investment in Solyndra turned a profit.

“It’s also a symbol of a serious conflict of interest,” Romney said.

KCBS’ Doug Sovern Reports:

Solyndra received $535 million in loan guarantees from the  Energy Department in 2009 only to go bankrupt last August, sparking an investigation.

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KCBS, CBS 5 and SF Chronicle Insider Phil Matier reports:

Romney’s appearance at the former Solyndra plant followed a meeting with Silicon Valley high-tech executives at the Rosewood Hotel in Palo Alto.

The Romney campaign staged the Solyndra event under extraordinary secrecy. The handful of reporters invited the night before to cover the event were required to undergo a background check.  Once they boarded Romney’s campaign , they were sworn to secrecy about its destination until the news conference.

Meanwhile, in Boston, Obama campaign strategist David Axelrod said at a news conference that Romney ushered in slow job growth, higher debt and more fees as governor of Massachusetts.

Axelrod was heckled by Romney supporters, who chanted, “Solyndra, Solyndra.”

Romney defended his gubernatorial record, saying the state’s unemployment rate dropped during his tenure.

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