The US Senate passed a defence policy bill on Wednesday that authorises the biggest pay raise for troops in more than two decades, but also leaves behind many of the policy priorities that social conservatives were clamouring for, making for an unusually divisive debate over what is traditionally a strongly bipartisan effort. Lawmakers have been negotiating a final bill for months after each chamber passed strikingly different versions in July. Some of the priorities championed by social conservatives were a no-go for Democrats, so negotiators dropped them from the final product to get it over the finish line.