Failing to avert the automatic spending cuts set to soon hit the Pentagon and other government agencies would be a "shameful" and "irresponsible" decision, Defense Secretary Leon Panetta said in an interview that aired Sunday.

"If Congress stands back and allows sequester to take place, I think it would really be a shameful and irresponsible act," Panetta said on NBC News' "Meet The Press."

The sequester is the roughly $1.2 trillion worth of cuts set to kick in soon if lawmakers don't act to avert them. House Budget Chairman Paul Ryan (R-Wis.) said last week that he thinks the sequester will happen. Panetta said the Pentagon is preparing for that possibility, but warned it would be a major setback for the military.

"We've got a plan for that possibility, because there are so many members that are saying -- you know-- 'we're gonna let it take place.' But I have to tell you it is irresponsible for it to happen," Panetta said. "I mean, why -- why in God's name would members of Congress elected by the American people take a step that would badly damage our national defense, but more importantly undermine the support for our men and women in uniform?"

Senate Majority Leader Harry Reid (D-Nev.) has said that any deal to avert the  sequester should include new revenue, a view that puts him at odds with Republicans.

"Without any question," Reid said on ABC News' "This Week With George Stephanopoulos," when asked if a deal to lift the sequester will have to include new revenue. He said that the other pressing fiscal issues Congress must confront, including addressing the nation's debt ceiling in the long term, must also include new revenue.

"I've got a pretty good fan base for that: the American people. Republicans, Democrats, and Independents," Reid said.

Reid's call for new revenues is at odds with congressional Republican leaders, who have said the issue of revenue was addressed in the recent deal to avert the "fiscal cliff" and has no place in the upcoming fiscal negotiations.

The Senate Democratic leader endorsed the idea of closing certain tax loopholes as means of generating new revenue.