Donald Trump’s victory in the Iowa caucuses was resounding enough to make the race for the Republican nomination look essentially finished at the start. But it wasn’t resounding enough to remove the sense that it could have been otherwise, that yet again his opposition within the Republican Party made things ridiculously easy for his candidacy.

Trump is essentially running an incumbent’s campaign, presenting himself as the default leader of the party, declining to debate, rolling up endorsements. But his opposition combined, it appears, for reasonably close to 50 percent of the caucus vote. And for a normal incumbent, losing almost half the vote in an early state would be a sign of danger, weakness, disarray.

Eugene McCarthy’s 42 percent of the New Hampshire primary vote in 1968 forced Lyndon Johnson out of the race. Ted Kennedy’s 31 percent in Iowa and 37 percent in New Hampshire in 1980 betokened a long and bitter campaign for Jimmy Carter. Pat Buchanan’s 38 percent against George H.W. Bush in New Hampshire in 1992 was regarded as a political earthquake, even though Bush cruised thereafter.

Combine the Iowa vote for Ron DeSantis with the vote for Nikki Haley, and even granting most of the support of Vivek Ramaswamy — who dropped out of the race Monday night — to Trump, you still have a total as impressive as those past anti-incumbent showings.