WASHINGTON — In a letter last month to President Barack Obama and congressional leaders, 11 Democratic and 11 Republican lawmakers, including Idaho’s Raul Labrador, asked that Defense Department spending be put squarely on the table in the coming clashes over debt reduction.

“We believe that substantial defense savings can be achieved over the long term without compromising national security, through strategic reductions in the Pentagon’s budget,” the lawmakers wrote in the letter.

Shifting fiscal and political pressures influence the emerging congressional coalition; approval ratings have hit historic lows among Americans upset by political gridlock.

But some military experts, both analysts who favor deeper spending cuts and those who oppose them, say there are additional reasons for the re-examination: The record federal debt, now at more than $16.4 trillion, has become a crucial priority that Pentagon leaders say affects military planning. At the same time, the national urgency over anti-terrorism has subsided as the Sept. 11 attacks recede into the chronological distance; the Iraq War has ended, the Afghanistan War is winding down and anti-terror efforts shift to new strongholds such as Mali and Yemen.

Lawrence Korb, who held a senior Pentagon post under President Ronald Reagan, sees a group of unlikely partners: Democrats who want to preserve social programs, tea party-backed Republicans focused on slashing the debt and libertarians aligned with Rep. Ron Paul — the Texas Republican and 2012 presidential candidate — who generally oppose U.S. military ventures abroad.

The congressional coalition has been at the center of a movement that’s stunted defense spending since its 2010 peak of $729 billion.

“The tide has turned,” Korb said.

First came the 2011 Budget Control Act, which imposed $487 billion in Pentagon funding cuts over a decade. It also directed Congress to find an additional $500 billion in reductions or accept forced across-the-board 8.6 percent cuts amounting to that total, now slated to start March 1.

Then, last July, the House of Representatives comfortably approved a one-year freeze on defense spending, with 89 Republicans joining 158 Democrats in voting for it. While the moratorium didn’t become law, it sent a signal that bipartisan resistance to unbridled military funding was rising.

Rep. Mick Mulvaney, a South Carolina Republican who helped spearhead the bipartisan letter, said it was intellectually dishonest for his party to protect the Pentagon while taking the knife to other large federal agencies.

“It undermines Republicans’ credibility on spending issues if we’re not willing to also look at the defense budget for possible savings,” said Mulvaney, who’s just starting his second term. “It’s hard to go home and say that we want to cut everything but not cut a penny on defense. People don’t believe that. More and more Republicans are willing to talk about this openly now.”

While the lawmakers who wrote last month’s letter have yet to get a response, the broader movement they represent alarms some defense analysts, who fear the pushback against military spending may go too far.

“By the time the Obama administration and Congress are done, we won’t have a big enough military to do what we need to do to remain a global power,” Thomas Donnelly, an analyst with the right-leaning American Enterprise Institute in Washington, told McClatchy.

Korb, though, said the Pentagon could easily absorb an additional $500 billion in cuts over a decade, which he said would take its budget down to 2007 levels when adjusted for inflation. He’d like to see Obama, lawmakers and top military brass find the cuts instead of having them indiscriminately imposed across the board.

“The defense budget went up so rapidly, they didn’t have to make any hard choices,” said Korb, who’s now a national security analyst at the liberal Center for American Progress in Washington. “They had waste like I’ve never seen. They spent $50 billion on weapons that they then canceled. Their cost overruns on new weapons systems were $400 billion to $500 billion.”