WASHINGTON – Senate Republicans are still considering who would benefit from changes to the U.S. tax code.

When asked, many of them were unable to communicate exactly which income brackets they would want to see reductions directed toward, instead using use catchall phrases such as "hardworking Americans."

The lack of specificity on the overall goal recalls the Republicans' failed health care effort, when they had difficulty agreeing on a unified objective beyond just repealing the Affordable Care Act.

Others said that the focus was on improving the overall economy and job creation, which could lead to relief in nearly every income bracket.

And some took the blanket approach of urging tax cuts for all, which could be difficult given the constraints Republicans are under with their slim margin in the Senate.

Some had direct answers. "Well-to-do people are going to be paying a lot more taxes," said Senate Majority Whip John Cornyn, R-Texas.

Republicans are using the budget procedure known as reconciliation to advance the tax legislation, which would allow the Senate to pass a bill with a simple majority.

But with just 52 seats, Senate Republicans can only afford to lose the backing of two members and still call in Vice President Mike Pence to break a tie. And several members have warned the Republican leadership of their limits.

Lawmakers such as Sen. Bob Corker, R-Tenn., have said that they would not vote for the measure if it adds to the deficit. Others have said that they would prefer not to operate under that constraint.

If Republicans do aim for a deficit-neutral plan, it would make it much more difficult to advance a bill that would rely on the theory that short-term deficits can lead to long-term economic growth.

Instead, they would be forced to find ways to pay for the tax cuts, inevitably creating a situation in which some taxpayers in some income brackets would pay less, while others might pay more.

Asked how they would determine which brackets would be affected, some Republicans were unable to say. "Hardworking men and women of America. The wonderful middle class," said Sen. Pat Roberts, R-Kan. "It depends on a lot of different things, but I think if you say middle class, everybody's got it pretty well figured out."

"It should benefit everybody, but including and especially ordinary people," said Sen. John Kennedy, R-La. "The middle class, the people who get up every day and go to work and obey the law and try to teach their kids morals."

One of the difficulties Republicans face is navigating the effect certain proposals would have on different states.

Removing the state and local tax deduction, for example, has become a huge point of debate in the party because some states, like Pennsylvania and New York, might be more adversely affected than others.

And without an exact idea of which income brackets should get the most relief, decisions on policy could be even harder.

The effort is still in the early stages, making it difficult to make definitive decisions on which income levels might be hit the hardest — or which would benefit the most.

Sen. Rob Portman, R-Ohio, said the cuts would most probably be felt in households that make over $100,000 a year.