WASHINGTON — House Republican leaders are struggling to devise a way forward on must-do legislation to increase the government’s borrowing cap.

GOP leaders have concluded that two of the top ideas to attach to the controversial legislation to build GOP support simply won’t work, so now they’re exploring another idea: repealing a recent cut to the pensions of working age retirees of the military.

GOP leaders had polled their members to see if they would vote to increase the debt limit if language requiring approval of the Keystone XL pipeline or repeal of a provision of so-called Obamacare were attached as sweeteners. But aides said there are too many Republicans who vow to oppose any increase in the borrowing cap.

The idea of repealing the military pension cut — a 1 percentage point cut in the cost-of-living increase for retirees under the age of 62 — appears aimed at winning the support of both Democrats and GOP conservatives. It passed the House in December with relatively little notice but was blasted by many Senate Republicans. Veterans groups are pressuring lawmakers to repeal it and have won supporters in both parties.

President Barack Obama says he won’t permit Republicans to use the debt limit as an engine to carry GOP priorities. Two debt limit increases were enacted last year with only modest add-ons like a provision forcing Senate Democrats to pass a budget.

GOP leaders like House Speaker John Boehner, R-Ohio, promise that there won’t be an economy-rattling, first-ever default on U.S. obligations. He’s tempering expectations that the GOP might be able to extract much in exchange for an increase in the government’s borrowing cap.

“The goal here is to increase the debt ceiling. Nobody wants to default on our debt,” Boehner said Tuesday. “But while we’re doing this, we ought to do something about keeping jobs in the economy, about the drivers of our debt.”

If Republicans controlling the House can’t unite and pass debt limit legislation on their own it would mean they’d need Democratic help to pass either a “clean” debt limit increase or one containing a fig leaf concession.

What’s more, time is running out. Treasury Secretary Jacob Lew warns that Congress needs to act by the end of the month and Congress is working an abbreviated February schedule.

Some Republicans see the handwriting on the wall and are willing to step aside and let the measure pass mostly with Democratic votes. Republicans also see political gain in keeping a focus on the trouble roll-out of Obamacare and aren’t interested in another battle along the lines of the one that precipitated the 16-day government shutdown last year.

“I do not want to get into a cataclysmic fight,” said Rep. Raul Labrador, R-Idaho.

Many Republicans had hoped to unite around a plan pairing a debt limit increase with language forcing the administration to approve further construction of the Keystone XL pipeline; another option involved a part of the health care law called “risk corridors.” Republicans warn that risk corridors, which protect insurance companies against the danger of big losses from insuring more people with pre-existing health problems, could lead to a potential bailout of the insurance industry.

But chances of the risk corridor option evaporated on Tuesday when the Congressional Budget Office said that the provision in the health care law actually would save taxpayers $8 billion over the next few years.

The aides requested anonymity because they weren’t authorized to publicly discuss GOP vote counts.