Cryptocurrency firms are facing a nightmare scenario in the Senate, where the shaky state of the industry’s top priority is threatening its plans to unleash midterm campaign cash against its enemies.

Republicans had projected confidence about advancing the legislation, which would overhaul federal regulation of crypto, before senators leave Washington for their summer break. But with just eight days to go, negotiators are still at odds on multiple fronts.

That’s a problem for the crypto industry’s network of super PACs, known as Fairshake, which had nearly $140 million to spend at last count. Its backers, which include firms like Coinbase and Ripple, were counting on a Senate vote on their long-sought bill to help settle whether all…