BRUSSELS — European Union officials, facing the rise of populist movements across the region, opted against hitting Spain and Portugal with sanctions on Wednesday for breaking the bloc’s rules on government spending.

The refusal to impose fines highlights how the 28-nation bloc is struggling with divergent strains of populist and anti-European forces across a region where one member state, Britain, has already voted to leave. The failure to issue penalties will also raise new questions about whether the European Commission, the executive arm of the European Union, has the political will to enforce its own rules.

Many economists have called on Brussels to ease the fiscal straitjacket, whereby countries face punishment if they run budget deficits beyond 3 percent of gross domestic product, to stimulate spending and to accelerate anemic economic growth across the region.

Nevertheless, the commission faced pressure to act against Spain and Portugal from some lawmakers in countries like Germany and the Netherlands who argue that a common currency needs commonly enforced rules to avoid the sort of sovereign debt crisis that was set off by the discovery of a large hole in Greece’s finances.