Former President Barack Obama delivered sharp criticism to fellow Democrats at a private fundraiser, urging them to abandon complaints and take concrete action. The remarks come as the party struggles to find effective opposition strategies during Trump's second term.

“It’s going to require a little bit less navel-gazing and a little less whining and being in fetal positions. And it’s going to require Democrats to just toughen up,” Mr. Obama said at a fund-raiser f...