By MATTHEW DALYWASHINGTON (AP) — A bill to protect health care and pension benefits for about 120,000 retired coal miners would save money over the next decade, according to a new report. The report by the nonpartisan Congressional Budget Office comes as bill supporters ramp up efforts to pass the measure by the end of the year, when they say thousands of mining families could lose benefits. The budget office's report says the bill would increase spending on health care and pension benefits for unionized miners and their widows by about $3 billion over the next 10 years. The cost would be offset by nearly $3.1 billion in new revenue generated by hiking customs fees on imported goods. Supporters say the bill would save lives and honor a 70-year-old promise made by the federal government. "This bill is simple — it is the continuation of a longstanding commitment by our government to lifetime health and retirement benefits for our miners," 22 senators wrote in a letter to congressional leaders urging swift passage. The letter was led by Democratic Sen. Joe Manchin and Republican Sen. Shelley Moore Capito, both of West Virginia. It was signed by 15 Democrats and seven Republicans. Nearly all Senate Democrats back the bill, which has divided coal-state Republicans. Several Republican incumbents supported the bill during the fall campaign, including Sens. Rob Portman of Ohio and Pat Toomey of Pennsylvania, who both won re-election. GOP leaders, including Senate Majority Leader Mitch McConnell of Kentucky, are wary of bailing out unionized workers. Sen. Rand Paul, R-Ky., also opposes the bill, saying he wants to provide relief for all coal miners, not just those who joined a labor union. The bill would ensure that retired miners receive more than $250 million a year in benefits now at risk amid the coal industry's steep decline and bankruptcies of several large companies. Without congressional intervention, some of the funds could run out of cash by next year, according to the United Mine Workers of America.