Senate Majority Whip Richard Durbin (D-Ill.), pauses during a news conference on Capitol Hill in Washington, Thursday, April 7, 2011. (Carolyn Kaster/AP)

Two historic pieces of legislation, overhauling the nation’s health-care system and rewriting regulations governing financial institutions, passed Congress last year after heated debate and intense lobbying. But even if the bills have departed Capitol Hill, the lobbying on them has not.

Companies and their backers are spending millions on lobbying hoping to roll back key provisions of the two laws, according to disclosure reports filed last week with the House and Senate.

In the first three months of this year, more than 300 companies, trade associations and lobbying firms were targeting provisions of the financial regulation law, records show. And more than 400 were lobbying on the health-care law, the reports show.

Those numbers are down from the peak of activity when the bills were taking shape, but the two issues are still among the hottest on Capitol Hill.

One of the biggest fights pits retailers against banks over the fees charged for debit card transactions.

An amendment that became part of the financial regulation law, sponsored by Sen. Richard J. Durbin (D-Ill.), gave the government the ability to cap the fees, which are paid to banks. The fees add up to a huge cost for retailers, restaurants and other businesses that accept payments by debit card.

That cap is expected to cost banks billions of dollars. As a result, lobbying on the Durbin amendment has only picked up since the Senate passed the measure on a vote of 64 to 33.

“It’s like the Hundred Years’ War,” said one lobbyist working on the issue who declined to be named, to avoid alienating his clients.

Visa reported spending $1.8 million on lobbying in the first quarter — its highest figure ever and a significant increase over the same period a year ago.

Because lobbying reports do not break out how much money was spent on each issue, it is impossible to know how much of that $1.8 million was spent on swipe fees. But 11 of the 13 lobbying firms hired by Visa did list the issue among the topics they were focused on.

Also, other related spending, including that devoted to public affairs and opposition research, is not included in lobbying figures.

MasterCard spent $930,000 in lobbying in the first quarter, up 13 percent from a year earlier. Visa declined to comment, and MasterCard officials did not return a request for comment.

On the other side of the issue, Wal-Mart, the nation’s largest retailer, reported spending $2.4 million in the first quarter, its highest figure and a 23 percent increase from the first quarter of last year. The company did not return a request for comment.

The battle over the fees has brought in all the weapons typical of a Washington legislative battle, including campaign money, constituent “fly-ins,” endorsement letters from an array of interest groups, media outreach and broadcast advertisements in lawmakers’ home districts.

The swipe fee debate is only one part of the financial regulation law that lawmakers and lobbyists are pushing to change. The House Financial Services Committee is considering legislation to delay the implementation of rules on derivatives trading and to change the structure of the Consumer Financial Protection Bureau, which was created in the law.

The health-care law, formally called the Patient Protection and Affordable Care Act, is also the target of a concerted lobbying push. While the full repeal proposed by House Republicans and recently approved in the House is unlikely to succeed, given opposition in the the Senate and the White House, several provisions of the law face a significant challenge.

Insurance brokers, who help companies purchase insurance and are paid through commissions, are lobbying to change a provision they view as threatening. The law requires that no more than 20 percent of health insurance premiums be spent on administrative costs, and brokers are pushing a bill that would exempt their fees from that cap.

The legislation, sponsored by Reps. Mike Rogers (R-Mich.) and John Barrow (D-Ga.), has drawn support from 58 other lawmakers.

“If the brokers win, consumers lose $1.4 billion in rebates,” said Ethan Rome, the executive director of Health Care for America Now, a coalition of groups that supported Democrats’ health-care proposals. “Brokers fees from our perspective are clearly an administrative expense, and Congress intended to categorize them as such.”

Brokers argue that the law has gone too far and would severely restrain their revenue. The president of the National Association of Insurance and Financial Advisors, Terry Headley, said in a recent speech that many of the brokers are small businesses that will be driven under unless the law is changed.

“Consumers will not benefit if agents are forced out of the market and individuals are left without service,” Headley said.

The main trade associations pushing for that change are spending roughly the same amount on lobbying that they spent last year when the full bill was under consideration.

Other parts of the law targeted by industry include a tax on medical devices as well as the Independent Payment Advisory Board, a key component of efforts to rein in costs. Device maker Medtronic spent $1.3 million in lobbying last quarter, up 22 percent from a year earlier. The company declined to comment.