Many Republicans are happy to do away with the deduction because it tends to benefit wealthy people in Democratic states that have high local taxes. But several Republican lawmakers also represent areas where constituents, including those in the middle class, make heavy use of the deduction. While Republican tax-writers remain committed to the idea, they are looking for ways to soften the burden on taxpayers who benefit from this tax break.

Lowering the cap on 401(k) contributions

The most recent idea to get caught in the game of legislative whack-a-mole was a proposal to dramatically lower the cap on the amount that workers can set aside in their 401(k) retirement accounts. Currently workers under 50 can set aside up to $18,000 a year without having to pay taxes up front on that money. House Republicans were discussing lowering that to $2,400.

This creates both practical and political problems. Lowering the cap on 401(k) contributions would save only a sliver of the $1.5 trillion in lost revenue from the tax cuts that Republicans are pushing. What is more, such plans are widely used by middle-class taxpayers that Republicans say they are trying to help. The idea died a quick death on Monday when President Trump said he would not let it happen.

Raising income taxes on the rich

The tax framework released by the “Big Six” Republican tax working group last month — the six lead negotiators from the House, Senate and Trump administration — called for three tax brackets with a top rate of 35 percent, down from 39.6 percent today. The plan kept open the option of creating an additional tax bracket for top earners to ensure the tax code remained progressive. No guidance was given on what that tax rate would be or what income level it would apply to.

Lawmakers, now facing criticism that their plan is a giveaway to the rich, are considering adding that additional bracket, potentially keeping it at the current 39.6 percent rate or slightly lowering or raising it.