The chief executives of Detroit’s struggling Big Three automakers returned to Capitol Hill Thursday to plead for a $34 billion taxpayer bailout. Speaking before the Senate Banking Committee, General Motors CEO Richard Wagoner asked for the biggest haul, totaling $18 billion.

Richard Wagoner: “To that end, our plan respectfully requests $12 billion in short-term loans and a $6 billion line of credit. We are seeking an immediate loan of $4 billion and potentially a second draw of up to $4 billion in January reflecting the current very weak state of automotive production and demand.”

GM says it faces bankruptcy without $4 billion in federal loans by the end of the month, with billions more needed in 2009. Lawmakers said they were not convinced that the automakers could return to profitability even with a massive infusion of government cash. Chrysler was next, asking for $7 billion by the end of the year. Ford says it doesn’t need an immediate loan but requested access to a $9 billion line of credit. The hearing was briefly interrupted when a group of protesters began yelling “the bailout is a sellout” before being removed from the room. The car company executives are set to appear again today before the House Financial Services Committee.