With the issue of the Affordable Care Act sure to play a major role in the U.S. Senate election in Louisiana this year, it’s no surprise that the best-funded Republican candidate, U.S. Rep. Bill Cassidy, recently released a campaign commercial highlighting his opposition to it — and to congressional shenanigans in the bargain.

But the campaign of Cassidy’s Democratic opponent, incumbent U.S. Sen. Mary Landrieu, says Cassidy is talking out of both sides of his mouth. The contention isn’t about his position on the health care law itself, on which the two candidates do disagree, nor even about the legitimacy of the collateral activity Cassidy deplores (which Landrieu has engaged in herself, to some extent): It’s about whether Cassidy is committing the political sin of hypocrisy.

Like a lot of things about the health care law, the dispute is complex, and firm judgments can be hard to come by. But the kerfuffle illustrates both the weight of the health care law as an issue and the meticulous scrutiny of the opposition that’s part of a highly contested political campaign.

The 30-second commercial opens with Cassidy, who is a physician from Baton Rouge, dressed in a white lab coat over green scrubs and talking to the camera about his 25-year career caring for charity hospital patients.

“I saw that when politicians and bureaucrats control health care, your care suffers,” Cassidy says. “Politicians know this. So some in Congress exempted staff from Obamacare,” he says, over an image of a 2013 Wall Street Journal article headlined, “Congress’s ObamaCare Exemption.”

“That’s what’s wrong with Washington,” Cassidy continues. “Let’s replace Obamacare with a health plan that gives power to you, not bureaucrats and politicians.”

Cassidy, like Republican candidates nationwide, hopes to capitalize on widespread discontent with Democratic President Barack Obama’s signature health care reform. Republicans in the U.S. House of Representatives, where they hold the majority, have introduced alternative proposals, but none of those measures has advanced through the legislative process.

Landrieu voted for the Affordable Care Act when it passed Congress in 2010, and she continues to support it, while arguing for some modifications, such as excusing more small businesses from the mandate for employee coverage. Cassidy voted in the solid Republican bloc against the 2010 bill.

What’s got the Landrieu camp in a swivet is Cassidy’s remark that “some in Congress exempted staff from Obamacare.” The Landrieu camp says that, actually, that “some” includes Cassidy himself.

The dispute has its roots in 2010, when the law was working its way through Congress. Republican Sen. Chuck Grassley, of Iowa, proposed an amendment that required the federal government to stop offering members of Congress and their staffs the governmentwide Federal Employee Health Benefits Plan — a typical workplace plan, with the employer paying about 75 percent of health coverage premiums and the employee paying the rest — but instead to “make available” only plans marketed through the health care law exchanges.

Grassley, who, like all Republicans, ended up voting against the Affordable Care Act, may have intended his amendment as a political ploy aimed at the Democrats, who would be embarrassed in rejecting it. But the Democrats called his bluff, if it was one, and included the amendment in the final version of the law.

That left the members and their staffs in a sort of limbo: Unlike every other large employer in the country, theirs could not offer them a standard workplace health plan and pick up most of the tab. The law, as written, did not seem to allow any employer contribution to the cost of their coverage (Grassley said later that was not his intent, and that what happened was the result of a drafting error by the Democrats).

Enter the Obama administration, via the federal government’s human-resources agency, the Office of Personnel Management. OPM promulgated a rule that said the government would continue to pay its share of the affected employees’ coverage provided they purchased it through the District of Columbia’s small-business exchange under the health law.

That, according to the Wall Street Journal and the anti-health care law media, is the “exemption,” a goodie that isn’t offered to any other health care law participants.

The Landrieu camp notes that Cassidy and his staff participate in the D.C. exchange and therefore enjoy the so-called exemption (although Cassidy says he donates his employer subsidy to charity). Landrieu herself does not participate in the D.C. exchange: She buys her coverage through a Louisiana exchange, receiving no employer contribution. She also receives none of the tax credits or subsidies provided through the Affordable Care Act itself; she couldn’t, under the regulations for Congress that apply to the health care law plans outside the D.C. exchange, but in any case, her Senate income of $174,000 exceeds the eligibility limits (set at 400 percent of the federal poverty level, which works out to $46,480 a year for an individual).

Like Cassidy’s staff, Landrieu’s regular office and district office staff purchase insurance on the D.C. exchange and receive the employer contribution. But there’s a wrinkle here, too.

As a Senate committee chairwoman, Landrieu also controls a committee staff. In 2010, she was chairwoman of the Small Business Committee, and she took advantage of a true exemption to the Grassley amendment to declare the committee staff “unofficial,” which meant they could remain under the Federal Employees Health Benefit Plan. Other committee chairmen and chairwomen did this, too; in fact, OPM has said the designation is up the member of Congress, and at least one House member reportedly has declared his entire staff “unofficial.”

Landrieu since has moved to the chairmanship of the Energy and Natural Resources Committee. The half-dozen committee staffers who migrated from the Small Business Committee are under the FEHBP, but those she brought from her own office to the energy committee are in the D.C. exchange, as no open-enrollment period has occurred yet to allow for any changes.

Cassidy has publicly declared his opposition to the employer subsidy for members of Congress and their staffs who buy coverage through the D.C. exchange. The Landrieu campaign says it is hypocritical for him to hold that position and then provide the subsidy for his own staff.

But it is far from clear that the option rests with Cassidy. While his staff members serve at his pleasure, they are not his employees: They are employees of Congress, and by extension, of the federal government. They are offered the health care law-with-employer-subsidy plan by virtue of that employment. As with any employee, they could decline that coverage and deal with their health-insurance needs by some other method —but it seems unlikely that Cassidy could require them to do.

For its part, the Cassidy campaign says that when its candidate refers to an exemption for congressional staff, he’s talking about the status of Landrieu’s former Small Business Committee staffers and others in the “unofficial” category. But the commercial muddies the water when it simultaneously displays the image of the Wall Street Journal article that applies the term “exemption” to the employer subsidy for health care coverage in Congress.

“Dr. Cassidy believes all politicians, including the president, his cabinet members and their staffs should be on Obamacare until we can repeal and replace it, no exemptions,” campaign spokesman John Cummins said in a statement. “When you pass a law but then have the executive branch decide it applies to some Americans but not others, the president creates a mess.”

Follow Gregory Roberts of The Advocate Washington bureau on Twitter @GregRobertsDC.