As Goldman Sachs executives sweated through tough questioning by a Senate panel, Democrats calculated that Republican resistance to the bill would crumble amid election-year pressures and widespread anger at Wall Street.
But they again fell short of the 60 votes needed to begin debate on the bill, which would effectively ban banks from several lucrative types of trading and subject them to greater oversight.
As on Monday, no Republicans sided with Democrats in the 57-41 vote. Key moderate Republicans said they had seen no developments to change their minds over the past 24 hours, and felt no pressure from voters to switch their position.
Another vote is expected tomorrow as Democrats try to cast Republicans as allies of a greedy Wall Street, perhaps the only address more unpopular with the public than Capitol Hill.
Lawmakers from both parties are eager to tighten oversight of the financial industry before the November congressional elections and many expect a bill will eventually pass.
President Barack Obama and his fellow Democrats want tighter rules to prevent a repeat of the 2008-2009 financial crisis.