PHILADELPHIA — Donald Trump’s plea to Russia to publicly release emails he suggested the Russians hacked from Hillary Clinton emerged as a major presidential campaign issue Wednesday, as former CIA chief Leon Panetta slammed the Republican nominee for urging a foreign power to meddle in U.S. politics.

“Donald Trump today once again took Russia’s side. He asked the Russians to interfere in American politics,” Panetta said. “Think about that,” he said, interrupted by chants from the convention floor of “No more war.”

Panetta served as Bill Clinton’s chief of staff and, in the Obama administration, he also pulled a stint as Defense secretary before moving to the CIA. These credentials made Panetta the point man of the night when it came to rebuking Trump on an area in which the Republican presidential nominee may be vulnerable: national security.

“Donald Trump, who wants to be president of the United States, is asking one of our adversaries to engage in hacking or intelligence efforts against the United States of America to affect an election,” Panetta said.

“As someone who was responsible for protecting our nation from cyber attacks, it is inconceivable to me that any presidential candidate would be that irresponsible. I say this out of concern for my children and grandchildren. Donald Trump cannot become our commander in chief,” Panetta said.

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The Russian hacking of U.S. emails resurfaced in the presidential campaign over the weekend when Clinton campaign officials — chair John Podesta and campaign manager Robby Mook — suggested that Russians were behind the embarrassing release of leaked Democratic National Committee emails showing staffers plotting against Bernie Sanders.

They hinted that the Russians did it to bolster Trump.

Trump said he didn’t do it, though no one exactly said he did. “It’s so far-fetched. It’s so ridiculous. Honestly I wish I had that power. I’d love to have that power,” he said at a Wednesday press conference in Miami at his Trump National Doral Resort.

Trump discussed about 30,000 emails that were deleted from the private email server Clinton used while secretary of State — which were not able to be retrieved by congressional and FBI investigators.

FBI Director James Comey announced earlier this month his decision not to recommend pressing charges against Clinton, the Democratic presidential nominee, a move affirmed by the Justice Department.

In Miami, Trump seemed to be encouraging Russia to do more.

“Russia, if you’re listening, I hope you’re able to find the 30,000 emails that are missing,” Trump said.

“I think you will probably be rewarded mightily by our press,” Trump said in his request to the Russians.

“. . . They probably have her 33,000 emails. I hope they do. They probably have her 33,000 emails that she lost and deleted because you’d see some beauties there,” he said. “So let’s see.”

In reaction to Panetta’s remarks, Stephen Miller, a Trump senior policy adviser, said in a statement: “It is alarming that Leon Panetta would, through his silence, excuse Hillary Clinton’s enablement of foreign espionage with her illegal email scheme and her corrupt decision to then destroy those emails and dissemble her ‘private’ server to hide her crimes from the public and authorities.

“He better than most should know how many lives she put at risk. At the same time, Panetta ignored Hillary Clinton’s rush to war in the Middle East and her deadly and calamitous invasion of Libya which further proves her a reckless risk too grave for any American family.”

Earlier in the day, after Trump commented on Clinton’s emails — her use of a private email server while secretary of State is a major issue for Trump — his running mate, Indiana Gov. Mike Pence, said the FBI “will get to the bottom of who is behind the hacking. If it is Russia and they are interfering in our elections, I can assure you both parties and the United States government will ensure there are serious consequences.”

Trump tried to soften his remarks a bit in a follow-up tweet:

“If Russia or any other country or person has Hillary Clinton’s 33,000 illegally deleted emails, perhaps they should share them with the FBI!” Trump tweeted.

Sen. Dick Durbin, D-Ill., told the Chicago Sun-Times that Trump “has a bromance with Vladimir Putin. For him to suggest that this man, who has caused so much damage and harm in the world should be invited to hack into an American citizen’s emails just shows you how far afield he is from reality.”

Jake Sullivan, Clinton’s national security adviser, said in a statement, “This has to be the first time that a major presidential candidate has actively encouraged a foreign power to conduct espionage against his political opponent. That’s not hyperbole, those are just the facts. This has gone from being a matter of curiosity, and a matter of politics, to being a national security issue.”