BERLIN (AP) — Germany's governing coalition has delayed a decision on a pension reform that has become a central ideological battleground, adding to questions over how long the government will last.

Chancellor Angela Merkel's center-right Union bloc leads a bad-tempered coalition with the center-left Social Democrats.

The two sides are struggling to find a compromise on a project to top up the pensions of low-paid people who have worked for at least 35 years. The Social Democrats say such payments should be made without means-testing, which the Union insists on.

A meeting scheduled for Monday to seal a compromise was delayed until Sunday. Social Democrat secretary-general Lars Klingbeil told ZDF television the coalition must agree on the project imminently and indicated that keeping the coalition going will otherwise be "a great deal more difficult."