With the government-supervised bankruptcy in June, 2009 making the U.S. GM’s (GM) largest shareholder, the automaker might be in line for a new capital structure and even a new major shareholder if the former Massachusetts governor wins on November 6. Why? The candidate has stated during his campaign that the U.S., which owns as much as a third of GM, shouldn’t be owning the automaker’s shares at all.

Romney, whose father was chief executive officer of American Motors as well as governor of Michigan, has attacked excessive regulation in the automobile industry. He has opposed federal fuel efficiency mandates, which the Obama administration has tightened, saying he prefers market-based solutions such as tax incentives. In July 2011 automakers representing 90% of U.S. sales agreed with the U.S. to a standard that would reach 54.5 miles per gallon by 2025.

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The Michigan-born former governor of Massachusetts has also criticized electric vehicles as “a technology that people aren’t interested in.” GM’s Chevrolet Volt “extended range” electric vehicle, whose production was encouraged by the Obama administration, has suffered from weak sales.

“The biggest changes could be an improvement in the macroeconomic picture during a Romney presidency” said a Detroit executive attending the Republican National Convention in Tampa, who declined to be identified. Assuming Romney achieves movement on the fiscal standoff in Washington, he said, the prospects for economic growth would be better. With economic growth, stronger demand for new vehicles is likely.

Assuming full dilution of GM warrants, options and preferred shares, the U.S. Treasury owns about 26% of the automaker, whose market capitalization stands at some $33 billion. The government, which spent $50 billion to finance the bankruptcy, would benefit from a gradual, orderly liquidation of its position — but nothing prevents the selling of its stake to a strategic investor, perhaps another automaker. (The U.S.’s latest estimate pegs the value of its investment at about $26 billion, implying a loss at the current stock price of near $24 billion.)

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A strategic investor paying $8 billion or so to own a quarter of GM quite possibly might insist on naming a new board of directors or at least a director or two. Restructuring of top management often follows appointment of new directors. An automaker such as China’s SAIC probably — already a GM partner — would likely salivate for a chance to own a chunk of GM. The politics of selling to a Chinese company would be hazardous, as the failed sale of Unocal to CNOOC demonstrated.

President Obama, should he win a second term, also might have good reason to liquidate the government’s position since he then would have little to lose or gain by holding on to GM shares. GM’s current management, while expressing gratitude for government financing of the bankruptcy and reorganization, has made clear that GM’s ownership is sometimes awkward. Federal oversight limits what GM can pay executives. The automaker has conceded that its surveys show that some consumers resist buying GM vehicles based on government ownership.

GM’s post-bankruptcy performance has been good, not great. U.S. market share has declined, its European subsidiary is racking up big losses and its CEO, Dan Akerson, has criticized the company’s profitability. Having gone through countless changes, including bankruptcy, from its heyday in the 1960s — yet one more may await if Mitt Romney, self-proclaimed “car guy” and son of Detroit, moves into the White House.