In YouGov’s three most recent surveys, Mr. Trump was viewed “very unfavorably” by an average of 43% of independents. How does he fare among moderate voters? In August, only 17% of moderates had a “very favorable” opinion of him; 47% had a “very unfavorable” opinion. Those figures have hardly budged since.

Ted Cruz doesn’t do much better. Only 13% to 16% of independents had a very favorable view of him in YouGov’s three most recent surveys; 28% to 32% viewed him very unfavorably. Among moderates, almost no one (6% to 7%) feels “very favorable” about Mr. Cruz; many (28% to 35%) feel “very unfavorable.”…

Already, large proportions of independents and moderates say that they have made up their minds about the two Republican front-runners. A full 58% of moderates and 51% of independents told YouGov in December that they “would never vote for” Mr. Trump. The figures are a little better for Mr. Cruz, but still about half of moderates (47%) and almost as many independents (41%) say they would never pull the lever for him.

How can anyone, under the circumstances, expect either of these two to win a general election? For the GOP to regain the White House, it will have to do much better, particularly given Hillary Clinton’s better ratings. In December, 48% of moderates said they would consider voting for Mrs. Clinton—a full 16 percentage points better than Mr. Trump and 22 points better than Mr. Cruz.