The pledge was to link any raise of the debt ceiling with equal deficit-reducing spending cuts, impose enforceable caps on federal spending and pass a balanced-budget amendment to the Constitution.

The former governor of Massachusetts wrote that he would aim for a spending cap at 20 percent of the gross domestic product (GDP).

“The steps we must take to undo the damage inflicted by Barack ObamaBarack Hussein ObamaOvernight Energy: Dems ask Pruitt to justify first-class travel | Obama EPA chief says reg rollback won't stand | Ex-adviser expects Trump to eventually rejoin Paris accord Overnight Regulation: Trump to take steps to ban bump stocks | Trump eases rules on insurance sold outside of ObamaCare | FCC to officially rescind net neutrality Thursday | Obama EPA chief: Reg rollback won't stand Ex-US ambassador: Mueller is the one who is tough on Russia MORE are as obvious as they are politically difficult,” Romney wrote. “A first step in reform is acknowledging that the federal government cannot be everything to everyone.”Romney, who has promoted his private-sector experience as the answer he would bring to the presidency, said the key to reducing federal spending and getting the deficit under control is to allow the private sector to take control of many of the programs that are failing in the public sector.

The op-ed appeared Thursday in New Hampshire's Union Leader newspaper, one of the key, early states in the election where Romney’s campaign has concentrated much of its recent efforts.