Mitt Romney’s campaign pushed back hard Wednesday against a highly sensitive ad produced by a pro-Obama ­super PAC that suggests a cause-and-effect relationship between Romney’s business practices and the death of a Kansas City steelworker’s wife.

The ad launched Tuesday by Priorities USA Action features former GST Steel employee Joe Soptic describing his wife’s swift death from cancer after he lost his job and health insurance when the steel plant — owned by Bain Capital, the private equity firm Romney founded — went bankrupt in 2001.

“Mitt Romney and Bain closed the plant. I lost my health care and my family lost their health care,” Soptic says in the ad. “And a short time after that, my wife became ill.”

Soptic adds he is unsure how long his wife was sick, saying “maybe she didn’t say anything because she knew that we couldn’t afford the insurance.”

By the time Soptic’s wife was examined by doctors, he says, her cancer was so advanced that “there was nothing they could do for her. And she passed away in 22 days.”

But contrary to Soptic’s assertion that his wife became ill “a short time” after GST Steel closed, Politico reported, Ranae Soptic died in 2006, five years after the plant closure.

And despite Soptic’s assertion that his family “couldn’t afford the insurance,” CNN reported that Soptic acknowledged in an off-camera interview that his wife’s employer provided her with health insurance after the steel plant was shuttered.

Later, Ranae Soptic tore her rotator cuff and left her job at a thrift store, according to CNN. It was then — not when Soptic lost his job — that she was left uninsured.

Even before these details were reported, the Romney campaign labeled the ad “contemptible” on Tuesday.

On Wednesday, the campaign accused President Obama’s aides of lying when they declined to condemn the ad, claiming not to know whether Joe Soptic’s story was portrayed accurately.

“This is an ad by an entity that’s not controlled by the campaign,” Obama campaign adviser Robert Gibbs said in an interview with MSNBC on Wednesday morning. “I certainly don’t know the specifics of this man’s case.”

“I don’t know the facts about when Mr. Soptic’s wife got sick or the facts about his health insurance,” Stephanie Cutter, Obama’s deputy campaign manager, added on CNN.

But two months ago, the Obama campaign featured Soptic on a conference call with reporters after launching a pair of ads spotlighting GST Steel. Cutter directed the press call, during which Soptic told the story of his wife’s death.

“With unemployment at a five-month high and stagnant economic growth, President Obama and his campaign are willing to say and do anything to hide the president’s disappointing record,” Romney campaign spokesman Ryan Williams said. “But they’re not entitled to repeatedly mislead voters. Americans deserve better — they deserve a president who’s willing to run an honest campaign and be honest about his own record.”

Romney spokeswoman Andrea Saul contended in an appearance on Fox News that if the Soptics had lived in Massachusetts “under Governor Romney’s health care plan, they would have had health care.”

As governor of Massachusetts, Romney led passage of a health care law that requires almost every resident to obtain health insurance and provides subsidies to people who cannot afford it on their own. But he has pledged to repeal a similar federal law, championed by Obama, if elected.

Priorities USA Action cofounder Bill Burton stood by his group’s ad in an interview with the Globe and said it was the Romney campaign that had stepped over the line.

“To use small details of this tragedy to make political points is really distasteful,” he said.

The point of the ad, Burton said, is that Romney’s business practices had long-term, harmful consequences.

Burton rejected the notion that the ad was designed to blame Romney for Ranae Soptic’s death.

Markey urges president ­ to safeguard electrical grid

US Representative Edward J. Markey called on President Obama on Wednesday to issue an executive order aimed at safeguarding the US electrical grid against cyber attacks.

In a letter to the president, the Malden Democrat urged Obama to grant additional regulatory authority to the Federal Energy Regulatory Commission. Markey argued new regulations are needed to compel electrical companies to bolster their cyber security protections.

“That way, we need not be at the mercy of an industry that has been inexcusably slow to act,” Markey wrote.

The White House did not immediately respond to a request for comment on Markey’s letter, but spokesman Jay Carney said last week that Obama would not rule out an executive order of the sort requested by Markey.

White House counterterrorism adviser John Brennan also raised the possibility of an executive order on Wednesday.

“One of the things that we have to do in the executive branch is to see what we can do to maybe put additional . . . guidelines or policy in place under executive branch authorities,” Brennan told the Council on Foreign Relations. “If the Congress is not going to act on something like this, then the president is going to do everything possible.”

Markey has been pushing for heightened cyber security regulations for more than two years. In 2010, he coauthored a bipartisan bill, known as the Grid Reliability and Infrastructure Defense Act, which directed the energy commission to impose tougher security requirements on electrical companies.

The bill was unanimously approved by both the House Energy and Commerce Committee, which Markey chairs, and the full House.

But the bill has been stalled ever since, a holdup Markey, in his letter to Obama, blamed on Senate Republicans’ acquiescence to utility-sector lobbyists.