Washington (CNN) - Top Senate Democrats have said they intend to keep the Senate in session Wednesday night as they try to formally open debate on a financial regulatory reform bill.
"We think it's critical to get to the debate. We think Wall Street reform must get done and must get done now," said Sen. Ben Cardin, D-Maryland. "We suspect that (Republicans) want to weaken this bill."
Earlier Wednesday, Republicans turned back efforts to launch Senate debate on such a measure. It was the third vote in 48 hours on the motion and, for the third time, unanimous Republican opposition decided the outcome.
Cardin said he didn't believe Democrats would force a vote to break a GOP filibuster until Thursday morning at the earliest. He indicated that Democratic leaders believe they are running out of time, however, to pass financial reform before members turn their attention to the looming midterm elections.
Ideally Democrats and Republicans "should work together," Cardin said. But unless the Senate starts debating the bill, "we'll never be able to consider it in a timely manner."
Cardin's announcement of a potential all-night Senate session came one day after President Barack Obama challenged Republicans to allow public debate on proposed financial reforms, telling an Iowa crowd that it's "not right" for the GOP to prevent the proposal from coming up in the Senate.
GOP senators say the proposal is too broad and needs to be tightened in closed-door talks with Democrats before coming to the Senate floor for debate.
"The American people deserve an honest debate," Obama told an Iowa crowd.
"You should not have to have to wait one more day."
Obama said Senate Republicans "unanimously blocked efforts to even begin debating reform."
"They won't let it [the bill] get on the floor to be debated," he said.
"It's one thing to oppose reform, but to oppose just even talking about reform in front of the American people and having a legitimate debate? That's not right."
The proposed reforms are intended to prevent another Wall Street meltdown like the one that led to the U.S. recession, Obama said.
"We can't let another crisis like this happen again," he said. "We can't have such a short memory that we let them convince us that we don't need to change the status quo."
Senate Democrats have accused their Republican counterparts of stalling momentum on the bill in an attempt to water it down.
One moderate Republican, Sen. George Voinovich of Ohio, has indicated he will switch his vote from "no" to "yes" if bipartisan negotiations on the bill between fail to reach agreement soon.
Updated: 4:01 p.m.