Thousands of unionized mine workers and supporters rallied at the Capitol Thursday to push for a bill that would protect health-care and pension benefits for about 120,000 former coal miners and their families. "We're here today to demand that the right thing be done!" thundered Cecil Roberts, president of the United Mine Workers of America, which organized the rally. "Keep the promise and pass the bill." Defying scorching 90-degree temperatures, Roberts and other speakers urged Congress to approve a measure they said would save lives and honor a 70-year-old promise made by the federal government. Marchers came from as far as Colorado and Nevada to demonstrate support for the bill, known as the Coal Miners Protection Act. Separately, Democrat Hillary Clinton announced her support for the measure, which would affect retired miners and their families in all 50 states, especially West Virginia, Pennsylvania, Kentucky, Ohio, Illinois, Indiana, Virginia and Alabama. The measure has near-unanimous backing from Democrats, but has divided coal-state Republicans. Several endangered Republican incumbents support the bill, but GOP leaders — including Senate Majority Leader Mitch McConnell of Kentucky — are wary of bailing out unionized workers. The bill would ensure that retired miners receive hundreds of millions of dollars in benefits now at risk amid the industry's steep decline, precipitated by competition from cheaper natural gas and tightening environment regulations. Without congressional intervention, some of the funds could run out of cash by next year, the union says. Sen. Joe Manchin, D-W.Va., noted that President Harry S. Truman brokered an agreement in 1946 to guarantee miners' lifetime health and retirement benefits, a move that averted a lengthy strike. "I assure you, we're not turning our back on you," Manchin said. Mary Lou Dersch of Oakland City, Indiana, traveled 15 hours by bus to attend the rally. Her husband, John, was a pumper at a coal mine in nearby Spurgeon before it shut down 15 years ago. Without the bill, Dersch, 61, and her husband, 63, face financial disaster. She called the rally "awesome" and said, "We're really hoping it does the job." Retired miner Dave Russell of Millfield, Ohio, wore a hat supporting Republican presidential candidate Donald Trump. Russell, 72, was unimpressed that Clinton supports the bill, while Trump has made no public comments on it. Trump's campaign did not respond Thursday to a request for comment. "I'm a Trump man all the way!" Russell said. "He says he's going to put coal miners back to work." Clinton said in a statement Thursday that those who have spent their lives "keeping the lights on for our country" should not be left "in the dark" once they retire. "They are entitled to the benefits they have earned and the respect they deserve," she said. Clinton has faced a backlash from coal communities after she declared earlier this year that she was going to "put a lot of coal miners and coal companies out of business."Clinton has said she misspoke as she tried to reassure voters that her policies would benefit out-of-work miners and other poor people in Appalachia affected by the coal industry's downturn. McConnell, a staunch defender of his home state's coal industry, has accused Democrats of waging a "war on coal." He denounced Clinton's comments as "callous" and "wrong." Still, McConnell blocked the pension measure last year and says he's not going to fast-track a plan that some Republicans warn amounts to a bailout. Sen. Mike Enzi, R-Wyo., chairman of the Senate Budget Committee, said he did not know why Congress should help the mine workers and not other private-sector pension funds. "Where do we draw the line?" Enzi asked. Wyoming is the nation's top coal producer — mainly from non-union plants — and Enzi said the bill would "do absolutely nothing for miners who are not members" of the UMW. Nearly 11,000 coal workers have lost jobs in the last year, according to the Bureau of Labor Statistics, and the pension bill "wouldn't help put those folks back to work," Enzi said. Sen Rob. Portman of Ohio, one of the endangered Republicans backing the bill, calls it a matter of fairness.