Congress and the White House agreed to the sequestration cuts as part of the 2011 debt ceiling deal that ended a showdown over whether to increase the federal government's borrowing limit to meet its obligations.
The automatic spending cuts never were intended to become law, but instead were designed to be so unwieldy and overbearing that Congress would reach a broader deficit reduction deal to avoid them.
Deep partisan divisions prevented such an agreement from happening in 2012, an election year. Initially the cuts were to go into effect on January 2, but the government delayed the impact of sequestration for the first two months of 2013.
In his speech, Panetta referred to what he described as "partisan dysfunction in Congress" that he said threatens the quality of life and national security of the nation.
Instead of making tough decisions to resolve problems, political leaders from both parties let issues become crises that require immediate but insufficient responses, he said.
"It's the easy way out," Panetta said, adding that there is a price to be paid for such an approach.
"You lose the trust of the American people," he said. "You create an aura of constant uncertainty that pervades every issue and gradually undermines the very credibility of the nation."
In another effort to stoke public alarm over the pending cuts, Carney told reporters that top defense contractors met at the White House with senior administration officials to discuss the impacts on their industry.
According to Carney, those impacts would be overwhelmingly negative.
"It's not just a parlor game here in Washington," he said of the issue. "These are real-world decisions that significantly affect the economy and the American people."
Obama said Tuesday that he still supports a broader deficit deal and made clear that revenue from tax reform measures previously agreed to by Republicans -- such as eliminating some loopholes to increase revenue for the government -- should be part of it.
Boehner, however, reiterated the GOP call for replacing the sequester plan with spending cuts and reforms -- a reference to changes in entitlement programs.
A last-second agreement in the previous Congress that passed in the first days of 2013 raised tax rates on top income earners as part of a limited deficit-reduction package.
That measure followed weeks of tough negotiations involving Obama and Congress in which other steps to increase government revenue, such as eliminating some tax breaks for corporations, were considered but not included in the final deal.
Obama and Democrats now want such revenue-raising steps to be part of a package that would replace the mandated deficit reduction of the sequester cuts.
McConnell expressed his opposition to such a move Tuesday, saying, "The American people will not support more tax hikes in place of the meaningful spending reductions both parties already agreed to and the president signed into law."