Hours after exit polls suggested health care was among the most important issues for Election Day voters in Virginia and New Jersey, lawmakers in the House's primary tax-writing committee debated language in the GOP's tax reform bill that would strip medical cost deductibility from the tax code.

The third day of the House Ways and Means Committee's tax reform markup kicked off Wednesday morning with the introduction of an amendment sponsored by Rep. John Larson, D-Conn.

Larson's proposed tweak to the tax plan would preserve a medical expense deduction that's included in the current tax code and allows Americans to write off certain medical expenses that exceed 10 percent of their gross adjusted income. The GOP's measure, which is widely expected to eventually clear the committee and proceed to a full House vote, would strip away that deduction.

"This is a direct assault on the elderly. It's no wonder the AARP has come out so strongly against this," Larson said Wednesday. "This is devastating to individual families."

For the second day in a row, Larson ended up getting into a heated exchange with his colleagues across the aisle, several of whom argued the deduction was only used by a small subset of people and that the lower tax rates and alleged pro-growth nature of the bill would be better for seniors and those with medical burdens than the current tax code.

"It appears to me that this amendment is politics, plain and simple," said Rep. George Holding, R-N.C. "In the context of tax reform, this targeted deduction is no longer vital thanks to the other tax benefits for seniors and all Americans provided in this bill. So what's actually critical to seniors are this bill's pro-growth policies, which will increase workers' paychecks and thus payroll tax revenues."

Particularly at issue for Larson was the idea that the GOP-led tax bill would strip away provisions like the medical expense deduction to fund tax breaks for businesses and wealthy Americans. He additionally brought up the plan's temporary doubling of the estate tax threshold – and the tax's eventual elimination – as evidence to back the argument that Republicans are looking to give wealthy Americans a handout.

Thomas Barthold, chief of staff for the bipartisan Joint Committee on Taxation, testified Wednesday that "any large estate would benefit" from such an adjustment.

"Meanwhile, you ask us to sit here and pay for – with these seniors – to pay for ... wealthy people who will be benefited from the estate tax repeal," Larson said, raising his voice. "That's what we're talking about here."

According to the AARP, nearly 8.8 million Americans utilized the medical expense deduction in 2015, with the average amount claimed sitting just north of $9,900. Nearly half of claimants reported annual income of less than $50,000, while 69 percent brought in less than $75,000.

And, indeed, the powerful lobbying organization hasn't been particularly receptive to this aspect of the GOP's tax plan. Gary Koenig, vice president for financial security with the AARP Public Policy Institute, wrote in a blog post Monday that the deduction's elimination "could significantly harm millions of middle class taxpayers, especially older taxpayers."

"This help that very sick Americans received through the tax code will now be redirected to some other folks who don't need the money," Rep. Bill Pascrell, D-N.J., claimed Wednesday. "Repealing this deduction is a tax increase on senior citizens in the United States of America – more specifically, our sickest seniors."

Yet even as much of the back-and-forth Wednesday morning was characterized by Democrats attacking Republicans for stripping away a tax benefit for sick and elderly Americans, those in the GOP continued to counter that their bill would leave more money in Americans' pockets to spend as they see fit.

"I take a little offense to my colleagues on the other side insinuating we don't care about the people we go to church with," said Rep. Tom Reed, R-N.Y. "What we're doing here is trying to do the best we can with making some hard decisions, but to insinuate we don't care – that we don't care about these people? … I care a lot about people. That's why I'm here."

Several others also pointed out Democrats previously supported an aspect of the Affordable Care Act that raised the threshold at which medical expenses could be deducted, from 7.5 percent of gross adjusted income to the current 10 percent.

"It's so fascinating. If the minority were as persuaded as they are today during the passage of the Affordable Care Act, why would they propose to make medical expenses more difficult to deduct?" said Rep. Peter Roskam, R-Ill. "If the ACA were working as it was proposed to work, much of this discussion wouldn't be necessary."

The odds of Larson's proposed amendment being included in the GOP-controlled House's tax package are slim for now, though Republicans in the Senate reportedly are aiming to preserve the medical expenses deduction in their forthcoming tax plan.

In the end, what is and isn't included in a final tax plan – should proceedings not be derailed by intraparty GOP divisions on issues like state and local tax deductions – may end up coming down to dollars and cents. Republicans will only be able to push a tax plan through the Senate with a simple majority vote if their bill's 10-year deficit hit doesn't exceed $1.5 trillion.