And the result? Many polls predict that her party, the Social Democrats, is headed for its weakest result in about a century — though, in the Danish multiparty system, Ms. Frederiksen should still manage to form a coalition and serve as prime minister for a third term. Since taking office in 2019, Ms. Frederiksen has transformed Denmark, greatly increasing military spending and establishing the country as a leader in the region. So why aren’t Danish voters ready to hand a sweeping victory to the woman who took on Mr. Trump?