House Republicans are eyeing a new fine on small businesses as their next Obamacare siege, now that the Supreme Court has squashed a challenge to the law's subsidies.

As Republicans orient themselves after the King v. Burwell ruling in late June — in which the court upheld a major part of President Obama's healthcare law, crushing GOP hopes of putting a big dent in it — they're contemplating how to broadcast their discontent with the law leading up to the 2016 election, when they hope to seize the White House and repeal it altogether.

One emerging possibility: a bill that would reverse a steep new IRS penalty on small businesses for helping to pay workers' health expenses through tax-free health reimbursement accounts, or HRAs, instead of sponsoring insurance plans directly.

Beginning July 1, businesses using the approach will be fined $100 per employee every day — which could add up to $36,500 for one worker over a year. The fine is capped at $500,000 annually, but opponents of the rule say that could cripple small businesses, which couldn't afford to provide full coverage in the first place.

"There is a lot of momentum around this," said Kevin Kuhlman, a lobbyist for the National Federation of Independent Businesses. "This is the biggest penalty no one has heard of, but now that [members are] becoming more aware of it, they're freaking out."

Republicans joined by some Democrats have voted dozens of times to repeal or change parts of the healthcare law, with the House voting on seven such measures this year alone. But unlike some pieces that have received lots of attention — like the medical device tax or the workweek definition — the HRA rule has flown under the radar.

The number of businesses affected is relatively small. Of firms smaller than 100 workers that don't provide coverage, about 14 percent help employees pay for health plans purchased on their own, according to a survey by the NFIB. There are an estimated 10.8 million health reimbursement accounts in the U.S., according to the Aite Group.

The National Association of Home Builders, another group lobbying hard against the penalty, estimates that 7 percent of its members offer HRAs.

But the issue may give Republicans the opportunity they're seeking to strengthen their case that Obamacare is hurting businesses. And two Democrats, Rep. Mike Thompson of California and Sen. Heidi Heitkamp of North Dakota, joined Republicans last week in rolling out House and Senate bills to scrap the penalty.

It's a "needed fix to restore the ability for small businesses, which sometimes can't afford to provide health benefits for employees, to help their workers purchase coverage using HRAs," Heitkamp said.

The healthcare law doesn't explicitly spell out the fine, but it does ban group health plans from capping annual benefits. The IRS says that's exactly what employers are doing by limiting contributions to workers' plans — even non-group plans purchased on the individual market— thus putting them in violation of the law.

That's unfair, according to small business advocates and lawmakers opposed to the penalty. Under the Affordable Care Act, businesses with fewer than 50 workers don't have to provide coverage to workers, but some still help employees cover their health costs by contributing to plans they buy on their own, which can be a cheaper option.

"Our members still want to help out their employees with healthcare, and in the past this has been a very popular option," said Suzanne Beall, a lobbyist for the National Association of Home Builders.

Employers helping workers with premiums or co-payments contribute an average of $950 for individuals and $1,800 for families annually, according to a Kaiser Family Foundation survey.

The smaller businesses could duck the new penalty by switching health contributions to taxable income. But opponents worry it will either cost workers contributions altogether or reduce them. And they say it cuts against the healthcare law's overall goal of getting more Americans insured by discouraging small businesses from helping pay for coverage instead of the IRS's intention to encourage them to offer plans directly.

"[The penalty] is more than most of our members report as revenue," said NFIB spokesman Jack Mozloom. "It's enough to wipe out a lot of them."

While Obama has vowed to veto most Obamacare repeal measures should they ever reach his desk, it's not clear how he would react to ditching the new HRA rule. It's not likely the Senate would take up the measure anytime soon, as Republicans there are considering whether to vote on repealing the entire healthcare law using budget reconciliation rules.

But aides and lobbyists say the bill might be headed for a markup in the House Ways and Means Committee this summer or after the August recess.

"It's something we'd like to do at some point," said Ways and Means spokesman Brendan Buck.