Congressional negotiators put their final signatures late Wednesday on an economic plan worth more than $150 billion that would extend a payroll tax holiday and unemployment benefits. A key roadblock was overcome when the lawmakers agreed to require new federal workers to contribute more to their pension plans, clearing the way for a majority of the House-Senate conference committee to approve the deal just past 11 p.m., aides in both parties said. A vote could come as early as Friday, the last act in a five-month battle over President Obama's proposed jobs plan.