WASHINGTON  The prospects of a government rescue for the foundering American automakers dwindled Thursday as Democratic Congressional leaders conceded that they would face potentially insurmountable Republican opposition during a lame-duck session next week.

At the same time, hope among many Democrats on Capitol Hill for an aggressive economic stimulus measure all but evaporated. Democratic leaders have been calling for a package that would include help for the auto companies as well as new spending on public works projects, an extension of jobless benefits, increased food stamps and aid to states for rising Medicaid expenses.

But while Democrats said the stimulus measure would wait until President-elect Barack Obama takes office in January, some industry experts fear that one of the Big Three automakers will collapse before then, with potentially devastating consequences.

Despite hardening opposition at the White House and among Republicans on Capitol Hill, the Democrats said they would press ahead with efforts to provide $25 billion in emergency aid for the automakers. But they said the bill would need to be approved first in the Senate, which some Democrats said was highly unlikely.