WASHINGTON - As a divisive year neared an end, Congress embraced hard decisions in the name of compromise.

Except for the part about the hard decisions.

In one head-snapping week, lawmakers from the Philadelphia area and across the country helped pass a bipartisan budget deal, then turned around and called for repealing a piece of that very deal.

In other words, many of the same lawmakers are reaching for credit on the compromise, and for cover on the details.

At issue is a two-year budget to keep the government running, a deal that undid a number of painful spending cuts and replaced them with largely inoffensive fees and substitute cuts, except for one: a 1 percent reduction in the cost-of-living increases in pensions military retirees receive until age 62.

Critics of that cut said it would, for example, cost a sergeant first class who leaves the service at 42 more than $70,000 over the next 20 years.

The cut, intended to save about $6 billion over 10 years, has prompted a widespread and fast-growing outcry, even from those who voted for the budget deal and its various components.

To lawmakers such as U.S. Reps. Mike Fitzpatrick (R., Pa.), Allyson Y. Schwartz (D., Pa.), and Jon Runyan (R., N.J.), the turnabout is an attempt to fix a flaw in a wide-ranging bill they otherwise supported.

"It's important to have a budget agreement," Fitzpatrick said in an interview, citing the economic certainty a two-year spending deal provides. "It's also smart to improve on it, and this is a smart, bipartisan, targeted way to do that."

Fitzpatrick - who faces a brisk 2014 reelection fight, including a potential matchup with former Army Ranger Kevin Strouse (if Strouse wins a Democratic primary against Shaughnessy Naughton) - voted for the budget plan, but then wrote his own bill to nix the pension cuts. He introduced it the day after the budget cleared the Senate. As of Thursday, he had 45 cosponsors.

Schwartz also supported the budget deal. But as she runs for Pennsylvania governor in a crowded 2014 primary field, she, too, called for undoing the pension cuts, signing on to another congressional Democrat's proposal to do so.

In explaining her position, a Schwartz aide pointed to the help the city and state would receive from the budgets' steps to avert cuts in health research (a huge share of those grants go to Philadelphia), early-childhood education, and other programs.

"The bipartisan budget agreement is a positive step toward replacing the damaging sequester cuts . . . but it is far from perfect," she said in a news release Thursday, arguing in the same release that the pension cut "unfairly targets our nation's military families."

"Schwartz Demands Restoration of Full Military Retirement Benefits," the headline on the news release said.

Neither lawmaker mentioned the pension issue when they sent out statements a week earlier supporting the budget deal.

To be sure, many bills pass with a mix of provisions - some popular, some not - and are later tweaked in the name of improvement. But neither of the fixes Fitzpatrick or Schwartz are backing has much chance of generating anything more than headlines.

Both would replace the cuts with alternatives that are beloved by their own party and hated across the aisle - thus having little chance of clearing a divided Congress. (Fitzpatrick's bill is identical to one the Senate rejected days earlier.)

There's a reason those ideas weren't in the original compromise.

This all stems from a modest deal struck by the budget czars in the House and Senate that would keep the government funded for two years, avert at least some of the deadline showdowns, and reverse some of the painful, indiscriminate "sequester" budget cuts.

To reach a compromise, negotiators put aside the big issues (tax increases, Medicare, Social Security) that would snag partisan trip wires, and settled on small steps nearly everyone could (and did) get behind.

Even as it undid budget cuts (immediately), the deal was projected to trim the deficit (with cuts that would take effect next decade - a frequent tactic for keeping bills in balance while leaving the pain for another day).

Angels didn't quite sing from the Capitol dome, but Washington congratulated itself for ending the year on a (relative) high note.

The plan passed the House and Senate in overwhelming fashion.

But even before the Senate voted, worries from the military community reached lawmakers' inboxes. Some senators attacked the bill as they prepared to vote for it.

Few wanted to be seen as blocking a compromise that would spare the country more fiscal fights. But few wanted to absorb the criticism that they were cutting soldiers' pensions.

We can only imagine the grainy attack ads and ominous voice-overs.

A stout few initially defended the pension cuts as the kind of hard choice needed to reach a compromise. They argued that the vaunted Simpson-Bowles commission had recommended entirely eliminating cost-of-living increases for military retirees under 62 as part of an effort to rein in fast-rising pension costs. Some said the change would largely affect military personnel (not all of them soldiers) who retired young and began second careers, or pointed out that the budget also included similar-size cuts in civilian federal workers' retirement benefits.

Those voices quickly faded.

Instead, from New Hampshire (Democratic Sen. Jeanne Shaheen) and Upstate New York (U.S. Rep. Dan Maffei, a Democrat) to the Florida panhandle (Republican U.S. Rep. Jeff Miller), lawmakers vowed to undo the military pension cuts.

The same cuts they'd voted for as part of the deal.

(The cuts, though, like most budget pain, are delayed: They won't take effect for two years, so opponents have time to try to undo them.)

Taken alone, it's easy to see the policy reasons for lawmakers' trying to protect benefits for military personnel.

But the political whiplash after a minor step toward budget peace also shows just how difficult it will be for lawmakers to embrace plans that take on the biggest challenges, and how hard it is for Washington to make hard choices stick.

@JonathanTamari