Democrats kept up their criticism of Mitt Romney's (R) approach toward the auto industry with a web video Thursday reminding Michigan voters that Romney had favored bankruptcy for GM and Chrysler.

The Democratic National Committee (DNC) released a new web ad, "Welcome to Detroit," featuring clips of Romney talking about how General Motors (GM) and Chrysler should have been forced into bankruptcy at the height of the crisis in the auto industry.

Romney is in Michigan, where he was raised and where his father was governor, on Thursday for public events and some fundraisers.

The former Massachusetts governor had written an op-ed favoring bankruptcy for GM and Chrysler in late 2008. Democrats have sought to use that piece against Romney in many of the key Midwestern battleground states, where the industry's impact looms large.

Of course, GM and Chrysler both did eventually file for bankruptcy, but it was a quick, preorganized process negotiated by the Obama administration and the leadership of the companies. Those bankruptcies were financed by the government, which took an ownership stake in each company.

Romney's presidential campaign has said that the administration was simply following a course that Romney had already charted; in his op-ed advocating bankruptcy, Romney favored a "managed bankruptcy" in which the government would guarantee financing for the companies.