Knowing what he knows, would Jeb like a second shot?

At this point in the campaign, do you see the Republican presidential hopeful who’s going to beat Hillary Clinton? I didn’t think so.

Not if what we’re watching now is the best they can do. Maybe a thoroughbred will emerge from the coming debates, assuming the party finds a way to cram all the candidates onto the same stage. So far, however, most of the GOP field seems to be in a contest to make the likely Democratic nominee look better. Jeb Bush has been the biggest disappointment. It’s one thing to be rusty after spending a few years away from politics; indeed, Clinton’s handling of her e-mail controversy was less than balletic. But Bush shows no sign of having given more than a passing thought to the central challenge he faces in reaching the White House: the fact that his brother got there first and made a mess of things.

Last week, Jeb Bush told an off-the-record gathering of potential donors and supporters that George W. Bush was one of his principal advisers on the Middle East. In essence, he was following his earlier “I’m my own man” declaration with a great big “Not entirely.”

This week, Bush struggled to deal with his brother’s biggest Middle East blunder: the invasion of Iraq. He sounded as if it had never occurred to him that someone might raise the subject.

Fox News anchor Megyn Kelly asked Bush whether he would have ordered the 2003 invasion knowing what he knows now. Bush answered a different question — whether he would have launched the war based on the intelligence available at the time. “I would have, and so would have Hillary Clinton, just to remind everybody,” he said. “And so would have almost everybody that was confronted with the intelligence they got.”

Actually, there were naysayers — among them an obscure Illinois state senator named Barack Obama — but never mind. On Tuesday, given another shot at the what-you-know-now question in a radio interview with Sean Hannity, Bush was again at a loss for meaningful words.

“Yeah, but I don’t know what that decision would have been — that’s a hypothetical,” Bush said. “But the simple fact is, look, mistakes were made, as they always are in life … and foreign policy.” He then declared that “going back in time and talking about hypotheticals, what would have happened, what could have happened,” was a “disservice” to U.S. war veterans.

Mistakes were definitely made in that answer, and other GOP contenders quickly piled on. Sen. Ten Cruz of Texas said that “of course” he would not have invaded because “the entire predicate of the war against Iraq was the intelligence that showed they had weapons of mass destruction and that there was a real risk they might use them.” New Jersey Gov. Chris Christie said that “I don’t think you can honestly say that, if we knew then that there was no WMD, that the country should have gone to war.” Sen. Rand Paul of Kentucky said it is “a real problem if [Bush] can’t articulate what he would have done differently” and declared that “I thought the war, even at the time, was a mistake.”

On Thursday, Bush finally said he “would not have gone into Iraq” — but added that the world is “significantly safer” because his brother did. Huh?

How could he not anticipate that his brother’s and father’s presidencies might occasionally come up? How could he not formulate a set of talking points on Iraq, commit them to memory and practice his delivery until it became pure reflex? Either Bush learns to deal with these dynasty questions, or the dynasty ends.

But hardly anyone is getting anything that looks like traction. There are far too many contestants to mention them all, but let’s start with Cruz, Paul and Christie, who remain stuck in the single digits in most polls. The same is true of former Arkansas Gov. Mike Huckabee. Retired neurosurgeon Ben Carson got a bump from his formal announcement, but since he has never held elective office and believes Obamacare is the worst thing since slavery, I’m betting his prospects are limited.

This leaves a top tier of Bush, who can’t get out of his own way; Wisconsin Gov. Scott Walker, who seems to be fading; and Sen. Marco Rubio of Florida, the flavor of the month, who hopes to win by propounding a robust, interventionist, Bush-like foreign policy, but without the whole Iraq part.

GOP to Hillary Clinton: Have a nice summer.

Eugene Robinson’s email address is eugenerobinson@washpost.com.