For more than a week, a first-of-its-kind bill to temporarily ban new A.I. data center construction has been sitting on the desk of Maine Gov. Janet Mills. In another era, the self-styled moderate might have already nixed the legislation. But the Democratic governor, who is also currently locked in a tight Senate primary race against the ultraprogressive oysterman Graham Platner, has come under enormous pressure from constituents on the left. Indeed, the scourge of data centers, which have been driving up electricity prices nationwide, has become an easy target for populists on both sides of the aisle. Mills has until April 24 to provide either a signature or a veto.