Washington (CNN) -- The House is expected to vote Tuesday on a scaled-back version of its original war funding bill, which would drop billions of dollars for unrelated domestic programs, including money to help struggling states avoid teacher layoffs.
Republicans and even some Democrats scoffed at additional spending being added to the bulging deficit. The contention was on full display last week when the Senate voted for a nearly $59 billion bill without the extra spending. The move resulted in the bill going back to the House.
The latest House-Senate dispute highlights the divide between the more conservative Senate and the more liberal House as well as the the frustration of House Democrats with the Obama White House.
Norm Ornstein, a congressional scholar at the American Enterprise Institute, said that the Senate by nature is more conservative and tends to have "an ego."
In addition, the House "can act faster and the Senate moves much more slowly," he said, referring to a stricter set of rules in the Senate on debates and amendments.
The divide also comes down to whipping up votes.
Right now, Senate Democrats need 60 votes in order to break a Republican filibuster and push a bill forward. There are 59 Democrats (including two independents) and 41 Republicans. The House, meanwhile, only needs a simple majority to pass a measure.
Because of that breakdown, Senate Democrats must all be on board and get a handful of Republicans to support their bill in order for passage.
It presents a challenge to liberal senators who often complain their voice is hushed, unlike their House colleagues.
The House has "a bit of a cushion in terms of the votes if they can't get any Republicans," Ornstein said.
House Democrats, meanwhile, find themselves in a tough spot this week, facing what Ornstein calls a "perfect storm of their having to cut back on spending and things like aid to the states or programs that they favor very much."
"They're being asked to vote for a war they don't like very much, and they're being pilloried by a lot of people for voting for those things," he said. "It's not very pleasant for them."
The House narrowly passed its $82 billion spending bill on July 1. Before the vote, the White House issued a veto threat, warning Democrats that President Obama would reject the bill if they placed money conditions that would "undermine his ability as commander in chief to conduct military operations in Afghanistan."
One amendment to the House bill, which would have forced the president to commit to a timetable for completing troop withdrawal in Afghanistan, drew strong support from 153 Democrats as well as nine Republicans. It was later defeated.
Obama has said he wants to begin reducing troops in Afghanistan beginning in July 2011. But he and Gen. David Petraeus, the top military commander in Afghanistan, have said the plan can change.
The White House, meanwhile, found itself on the defense Sunday after WikiLeaks, a whistle-blower website, published what it said are about 76,000 U.S. military and diplomatic reports about Afghanistan filed from 2004 to January 2010.
The firsthand accounts are the military's own raw data on the war, according to Julian Assange, the founder of WikiLeaks.org, which published the material Sunday.
Assange later said the leaked reports appear to contain "evidence of war crimes."
Ornstein said that the unease for House Democrats, already concerned about the war in Afghanistan, is going to be amplified by the recent news.
But congressional watchers note that while there are concerns, the stripped down bill will end up passing as it garners greater Republican support this time around.
CNN's Evan Glass, Brianna Keilar and Deirdre Walsh contributed to this report.