Washington (CNN) -- Three days before forced spending cuts portrayed by most as an economic body blow, President Barack Obama and Republican rivals relied on spin versus substance Tuesday in trying to prod a deeply divided Congress into action to avert the harshest impacts.
Government officials and military leaders continued warning of serious consequences if Congress fails to agree on an alternative to the mandatory $85 billion in cuts for the rest of fiscal year 2013, which ends on September 30.
Federal Reserve Chairman Ben Bernanke said Tuesday the automatic cuts will slow the already sluggish economy, harming the still-moderate recovery from recession.
Meanwhile, Immigration and Customs Enforcement said it will release "several hundred" immigration detainees to "less costly" forms of supervision because of the imminent cuts, known in Washington jargon as sequestration.
That brought immediate protests from some conservative Republicans. Arizona Gov. Jan Brewer called the move "pure political posturing and the height of absurdity."
Republican leaders have criticized Obama administration warnings as scare tactics, but also said the cuts would be bad policy and should be changed. Only rigid fiscal conservatives have backed the concept of mandatory deep spending cuts as a painful first step of deficit reduction.
Obama headed to military country in Virginia, where local residents will bear the brunt of cuts to defense spending, to urge Newport News shipyard workers to pressure Congress for a solution.
Insisting he wasn't interested in political spin, Obama acknowledged the cuts set to take effect Friday "won't be felt overnight, but it will be real," adding it means lost jobs and weakened national security.
He called the situation "a self-inflicted wound that doesn't have to happen," saying the goal of reducing the federal deficit can be achieved in a smarter way if Republicans will compromise on including additional tax revenue as part of the solution.
"I need you to keep up the fight. If you do, Congress will listen," said Obama, who spoke with a huge ship propeller as a backdrop.
Meanwhile, House Speaker John Boehner expressed continuing frustration over what he called a lack of leadership by Obama and Senate Democrats.
The House passed two bills in the last Congress that would have replaced the mandatory cuts of sequestration with other reductions that avoid harming the military, a concept rejected by Democrats as shifting the impact of deficit reduction to the middle class and needy Americans.
"We should not have to move a third bill before the Senate gets off their ass and begins to do something," Boehner told reporters on Tuesday.
In response, House Democratic leader Nancy Pelosi of California said bills passed by the previous Congress no longer matter, and that the Constitution requires legislation involving appropriations and revenue to originate in the House.
"There's not much that is being accomplished by what they are doing," Pelosi said of House GOP leaders, calling their refusal to act on the matter "irresponsible" and "mindless."
The forced cuts were written into law in 2011 to be intentionally indiscriminate so that legislators would compromise on an alternative instead of allowing them to take effect.
However, election year politics in 2012 prevented an agreement, and the continuing partisan divide over how to reduce or at least control chronic federal deficits and debt caused the widely opposed spending cuts to become imminent.
Conflicting messages in the increasingly heated debate raised confusion about exactly what will happen if the spending cuts go into effect.
At a House subcommittee hearing on Tuesday, the heads of the nation's military services warned of serious problems if the full effect of cuts are allowed to happen.
Gen. Ray Odierno, the Army chief of staff, said the pending cuts would hollow out the military and were "not in the best interest of our national security."
In particular, he said reduced spending for this year would reduce training, diminish the special operations command and result in layoffs and furloughs of civilian staff that will delay medical care for soldiers and their families.
Rep. Harold Rogers of Kentucky, the GOP chairman of the House Appropriations Committee, told the panel that the spending cuts were "both terrible politics and terrible policy" that would impair the nation's overall military readiness.
That contrasted with conservative Sen. John Cornyn, R-Texas, who said Monday that the cuts won't be as harmful as the Obama administration warns.
The veteran senator conceded that he initially agreed with dire predictions from the administration and top Republicans of major harm to the nation's military. After looking into the situation, Cornyn said he now argues that the Pentagon will still see its budget go up despite the forced cuts.
Senate Republicans are considering a proposal this week that could alleviate some impacts of the cuts by giving the president flexibility to decide where they would occur.
The proposal is the GOP counter to a Democratic plan to replace the sequester with more tax revenue collected from millionaires, as well as eliminating agriculture subsidies and reducing defense spending after the end of combat operations in Afghanistan next year.
Under the law that created the forced spending cuts, neither the Pentagon or government agencies can shift money to protect some programs or operations from reduced funding.
While Republicans are divided over how much flexibility Obama should get to avoid the worst impacts of the cuts, they appear unified in opposing any increase in tax revenue to partially offset them.
A January agreement that raised tax rates on top income earners while putting off the forced cuts for two months provided all tax revenue Republicans were willing to consider, party leaders say.
"We can either secure these reductions more intelligently or we can do it the president's way with across the board cuts," Senate GOP leader Mitch McConnell said Tuesday. "But one thing Americans simply will not accept is another tax increase to replace spending reductions we already agreed to."
Obama addressed that viewpoint in his remarks in Virginia, saying there were "too many Republicans in Congress right now who refuse to compromise even an inch when it comes to closing tax loopholes and special interest tax breaks."
"That's what's holding things up right now," the president said. "Keep in mind, nobody's asking them to raise income tax rates. All we're asking is to consider closing tax loopholes and deductions that (Boehner) said he was willing to do just a few months ago."
The full impact of the cuts won't be felt for at least a month, until after a March 27 deadline for Congress to agree on extending funding for the government for the rest of the fiscal year.
An agreement on the overall government funding could soften or eliminate the cuts and much of the hyperbole this week involved posturing for the broader debate of coming weeks.
CNN's Carol Cratty, Dana Bash, Alan Silverleib, Ted Barrett, Kevin Liptak and Ashley Killough contributed to this report.