The agreement came as a poll revealed strong opposition to a pension age hike, with just 7 percent of Germans saying they were happy to retire at the age of 67, and most saying they actually wanted the age lowered.
Daily Bild reported Wednesday Gabriel and Steinmeier had agreed that their policy should include an incremental increase in the retirement age beginning in 2015 at the earliest, not 2012 as planned by Chancellor Angela Merkel's centre-right coalition.
The centre-left Social Democrats (SPD) would also want the year 2029 to remain the date by which the full increase needed to be implemented – the same as the original plan.
The issue had become a thorn in the side for opposition party, which agreed to a rise in the retirement age when it was part of the former “grand coalition” government with the conservative Christian Democrats, but has since had doubts.
The pension age is a pivotal issue for a country with an ageing population and a sinking ratio of workers to retirees, but remains a politically sensitive subject for the left side of politics. The SPD was essentially torn apart five years ago after many members, disaffected by the then leadership's embrace of a pension age increase, defected and joined the socialist Left party.
Gabriel and Steinmeier plan to put forward their compromise plan to the party leadership this Sunday and then to the full party conference in September.
Gabriel has lately spoken out in favour of deferring the planned increase in the pension age on the grounds that the job market is not strong enough to support more workers in the autumn of their careers. He has argued it should be put off until policymakers can be sure a large share of elderly people can actually find work.
Steinmeier, on the other hand, has emphasized the need for people to work longer, and defended the grand coalition's original blueprint. SPD vice chairman and Berlin mayor Klaus Wowereit, meanwhile, called for complete renunciation of lifting the pension age from 65 to 67.
Polls show the public to be firmly against an increase. A survey published in Stern magazine showed just 7 percent of voters want the age raised to 67.
Some 38 percent wanted to kept at 65, but even more people wanted to see it lowered. Some 21 percent said it should be lowered to 62 and 24 percent thought 60 was a good age to set retirement.
The environmentalist Greens parliamentary leader, Renate Künast, said she continued to support the plan to raise the pension age starting in 2012.
“I don't want to change anything about the increase, because generational justice is very important to me,” she told the Kölner Stadt-Anzeiger. “We are well advised to the stick to this moderate time frame.”