GOP blasts bill, but measure may be Democrats' opening proposal for negotiations toward a compromise measure.

Plan sharply different from House-passed bill, which creates new federal loans for troubled pension plans.

PBGC says its 2016 multiemployer program deficit grew to $58.6 billion from 2015's $55.5 billion.

Pension advocacy group says local's early retirees would be hit particularly hard, facing cuts of up to 60%.

Decision is Treasury's first benefit-cut approval under 2014 multi-employer pension law.

Decision is the first under 2014 law allowing weak multiemployer plans to apply to reduce members' benefits.