People watch as Donald Trump speaks at a rally in May in Bismarck, N.D. (Spencer Platt/Getty Images)

There are any number of pathetic voices trying to rationalize support for Donald Trump. He is better than Hillary Clinton! (Really, how exactly?) The Supreme Court! (What about it? Trump shows no commitment to any judicial philosophy and is just as likely to make a deal with Democrats to get something he cares about.) He could pick stellar advisers! (They wouldn’t work for him, and if they did, he’d ignore them.)

It seems one argument even Trump’s most strident defenders can make is: He’s the best candidate to beat Hillary Clinton. Actually, he’s the worst, and it would be politically suicidal to nominate him when other credible contenders are readily available.

Ballotpedia’s polling conducted battleground-state polling with a two- and three-way race, comparing how Trump, Ohio Gov. John Kasich and House Speaker Rep. Paul Ryan (R-Wis.) would do:

In all seven states, Clinton polled higher than Trump. The tightest battleground race between the two frontrunners was in Iowa, where Clinton leads Trump by a weighted 4 percentage points. Clinton saw the largest lead in Michigan, where she leads Trump by a weighted 17 percentage points. Comparatively, John Kasich polls ahead of Clinton in five of the seven states, and Paul Ryan polls ahead of Clinton in three states.

In addition to the weighted survey results, we conducted predictive modeling. . . . These results demonstrated that Donald Trump would underperform Hillary Clinton by an average of 10 percentage points, versus John Kasich outperforming Clinton by 4 points and Paul Ryan outperforming her by 1 point. Using this model, Kasich would be predicted to win six of the seven states and would be even with Clinton in just North Carolina.

The fantasy that Trump would “rewrite” the map and take Rust Belt states away from Clinton helped him win the GOP nomination. But the reality is far different. Trump does worse than Mitt Romney among groups Republicans should win and far worse among groups with which Romney was competitive.

The real issue for the delegates is this: Do they assure that the GOP will suffer a stunning loss with a candidate who risks maligning the entire party, or do they act responsibly to make certain that the GOP has a competitive chance to win the White House? It just so happens that the alternatives to Trump who likely do better against Clinton are also more prepared, more conservative, more ethical, more articulate, more optimistic, more likely to choose better advisers, more likely to accomplish conservative aims, more likely to find judges at all levels who reflect a conservative judicial philosophy, more likely to avoid a meltdown during the rest of the campaign and the debates and more likely to raise sufficient funds and put together an adequate campaign team.

If the delegates believe they have no role and must rubber-stamp the primary totals, then they should not bother to go to the convention; they are superfluous. They need to embrace the role they were selected to perform: conscientious guardians of the party’s 2016 presidential prospects. They have a variety of options, including forcing Trump to release his tax returns. If he refuses, it will be he who is rejecting the nomination.

If, however, the delegates leave Cleveland with Trump as the party’s nominee, they would have failed the GOP, the conservative movement and the country. They would also be guilty of political malpractice on a scale not seen in the modern era.