WASHINGTON—A bipartisan group of U.S. senators on Thursday proposed an amendment to an annual defense policy bill that would impose a diplomatic boycott of China’s Winter Olympics—less than 100 days away—amid accusations of rights abuses by Beijing. The amendment, led by Republican Senator Mitt Romney, mirrors language included in sweeping China-related legislation the Senate passed in June, and would prohibit the secretary of state from spending federal funds to “support or facilitate” the attendance of U.S. government employees at the Games. But with the Olympics set to open in February, the fate of that measure is in limbo. With Congress preoccupied with President Joe Biden’s domestic agenda, the bill passed by the Senate has stalled in the House of Representatives. The new amendment, if approved, would add the diplomatic boycott provision to the 2022 National Defense Authorization Act (NDAA), a defense bill Congress has passed every year since 1961. The …