Updated: 6:54 p.m.

Senate Democrats and House Republicans clashed today over who would be to blame if the two sides can’t agree on disaster aid funding in a stopgap spending bill and the government shuts down Oct. 1.

Even as they tried to shift the responsibility to each other, leaders in both chambers were struggling to find the votes for their respective proposals.

House passage of the continuing resolution is not guaranteed. More than 50 House Republicans are expected to defect from their leadership and vote against it, charging that the $1.043 trillion total is higher than what was set out under the GOP budget approved earlier this year. They are taking that position despite pleas from House leaders, including Majority Leader Eric Cantor (R-Va.), to accept the higher spending caps agreed to in last month’s debt ceiling bill.

With those defections and potentially more from Democrats who are holding out for more disaster money, it’s now unclear whether House Republicans have the 218 votes they need for Wednesday’s floor vote or to pass a CR with additional emergency spending included.

If it does pass, Senate Majority Leader Harry Reid (D-Nev.) will face troubles of his own. Reid said today  he could not say for certain that Congress could act in time to prevent a government shutdown before the Sept. 30 deadline to renew funding for federal programs and agencies.

“I am not that sure,” Reid said during his weekly press conference. He blamed House Republicans looking to appease their tea party base.

“We are not going to back down,” he said of the Senate Democrats’ push for $7 billion in disaster aid that is not offset.

Reid also threatened to keep the Senate in session during next week’s scheduled recess to resolve the issue.

But Cantor told reporters a shutdown would be the fault of Senate Democrats, who he said were looking to score political points.

“It’ll be on Leader Reid’s shoulders because he’s the one playing politics with it,” Cantor said today. “There’s nothing else but politics going on with that move if that’s what happens.”

At issue is the disaster funding provision in the continuing resolution that the GOP-led House is expected to send to the Senate on Wednesday. The CR would fund the federal government through Nov. 18.

The House CR includes $3.6 billion for Federal Emergency Management Agency funding. The bill also offsets about $1 billion of that spending by cutting the Department of Energy’s Advanced Technology Vehicle Manufacturing loan program, which helps the auto industry retool or expand factories to produce fuel-efficient technology.

Senate Democrats contend that the $3.6 billion disaster level is inadequate, they oppose the ATVM offset, and they argue that House Republicans are reneging on the August debt ceiling agreement, which provided a cushion of about $11 billion for emergency spending.

Reid intends to try to amend the House CR with legislation passed by the Senate last week that would provide nearly $7 billion for disaster aid.

But it’s unclear whether Reid will have the votes to add the Senate disaster package. Last week, 10 GOP Senators voted with Democrats to pass the measure 62-37. But at least three of those Republicans — Sens. Roy Blunt (Mo.), Dean Heller (Nev.) and Susan Collins (Maine) — said today that they were undecided. Reid can only lose two votes and still be able to secure the 60 votes needed to clear any attempted filibusters.

“This week, I am hopeful that we will see the same Senators vote for a bill to keep the government running and avoid the kind of political brinksmanship that marked this vote last time around,” Reid said. “The money provided in the House bill would fund FEMA for just a few weeks, not months. It certainly won’t go into next year.”

His comments come as 48 states have experienced disasters this year, and FEMA is running low on funds. FEMA now only provides aid for immediate disasters and has halted the rebuilding of areas damaged by past disasters.

Sen. Mary Landrieu (D-La.) said that there is a backlog of thousands of projects that are on hold.

“Right now people need help,” Landrieu said, adding that she is puzzled at House Republicans’ position because the deal to raise the debt ceiling allows Congress to provide about $11 billion over spending caps for disasters.

“We are asking to use $6.9 of that $11 billion,” Landrieu said. “So you have to ask yourself, ‘Why are they doing this?’”

Sen. Debbie Stabenow (D-Mich.) warned that the proposed House offset would hurt job creation.

“It’s outrageous that House Republicans are pushing a plan that would gut an initiative proven to create thousands of jobs in Michigan and across the country, and that they are trying to ram it through by attaching it to disaster relief,” Stabenow said in a release. “These loans have helped our businesses transform abandoned factories to build new high-tech products here at home instead of overseas. Congress should cut waste and government programs that don’t work, not end incentives that help businesses keep jobs in America.”

Sen. Carl Levin (D-Mich.) said he hopes the 10 GOP Senators vote for their constituents rather than their party.

“I think changing your vote always looks bad and I don’t see how it could be justified here,” Levin said. “This is an extremely important jobs provision.”