A Republican lawmaker said this week that the discussion around his party's tax bill is flawed. Most of the public's attention has been on who among the poor, the middle class and the rich gets a tax cut and who gets a hike. The real story, Rep. Mark Sanford (R-S.C.) said Tuesday, is that the Tax Cut and Jobs Act is about helping businesses.

“Fundamentally the bill has been mislabeled. From a truth in advertising standpoint, it would have been a lot simpler if we just acknowledged reality on this bill, which is it’s fundamentally a corporate tax reduction and restructuring bill, period,” Sanford said.

The bill costs close to $1.5 trillion. The bulk of that money — about two-thirds — is going to pay for lower tax rates for businesses. Both the House and Senate versions of the bill drop the top corporate tax rate from 35 percent to 20 percent, the biggest one-time reduction ever in the business rate.

For the most part, companies have cheered the Republican tax bills ever since the House first introduced its plan on Nov. 3. The Dow Jones industrial average rose over 700 points (3 percent) in November. But much of the euphoria stopped in the wee hours of Saturday morning, when the Senate hurriedly passed its bill and business leaders woke up to realize they weren't getting such a great deal after all.

The biggest last-minute change the Senate made was to keep the corporate alternative minimum tax (AMT) at 20 percent — the same rate as the new, massively lower business tax rate. What that means is many businesses would not be able to take deductions and credits to lower their tax bill below 20 percent.

In short, the AMT neutralizes many of the other incentives like the research and development (R&D) credit that were meant to encourage companies to build new factories and expand their operations and jobs in the United States.

“It turns out that in their rush to get a bill done, the GOP senators shot their donors in the foot and perhaps in more sensitive places as well,” wrote Michael Block, chief strategist at Rhino Trading Partners, in a note Monday. “Some genius in the wee hours on Friday night kept a 20 percent AMT for corporations in the bill. In doing so, they may well end up raising taxes for many corporations.”

Manufacturing companies — the very businesses President Trump vowed to help in the campaign — would be hit especially hard.

“Research and development is the lifeblood of manufacturing,” said Chris Netram, vice president for tax and domestic economic policy at the National Association of Manufacturers, which represents 14,000 manufacturing companies.

A half-dozen lobbyists who spoke on the condition of anonymity because they are not authorized to speak publicly describe frantic calls Monday as companies from tech to industrials tried to figure out how to get Republicans to fix the bill. By Wednesday, top executives were talking with Gary Cohn, Trump's top economic policymaker, and Senator Patrick J. Toomey (R-Pa.).

“These are nontrivial issues. If they are not fixed, you have a very bad bill on your hands,” said one lobbyist. “Company after company was saying on the call that this makes no sense.”

The National Association of Manufacturers sent a letter to Rep. Kevin Brady (R-TX) Wednesday that said "the top federal statutory corporate tax rate should not exceed 15 percent. This rate would make our nation’s manufacturers much more competitive in the global marketplace."

The corporate AMT has received the most attention, but it's far from the only issue alarming the business community. Many companies are also concerned by how much the Senate bill limits their ability to deduct the interest costs of their debt from their taxes. Corporations routinely borrow money to finance new factories, equipment and research projects similar to the way many Americans borrow to buy homes. Curtailing that deduction takes away some incentive to invest more in the United States.

Some companies, especially manufacturers, are also concerned about new taxes that Republicans want to put in place to make it harder to import goods. The House bill initially proposed a 20 percent excise tax on things a U.S. company buys from its foreign subsidiaries, but that was mostly gutted by the time it passed. The Senate plan includes a 10 percent Base Erosion Minimum Tax to prevent American companies from using credits and deductions, including from foreign subsidiaries, to get their tax bill below 10 percent.

The goal is to prevent U.S. companies from shifting profits overseas to lower-tax countries, but businesses say it disrupts the global supply chain and would lead to higher costs for customers. In the auto sector, for example, many companies import microchips or small steel parts that they say aren't made in the U.S. Bringing these parts into the country then creates jobs and business in the U.S. because the parts are combined with American-made products and ultimately put into American-made cars.

“We think it would be a mistake for them to keep pursuing base erosion and excise tax provision. That defeats the whole point of freeing up more capital for manufacturing investments and jobs here in the U.S.," said Tom Lehner, vice president of policy at the Motor & Equipment Manufacturers Association, who has 1,000 companies. Auto suppliers employ over 800,000 Americans.

As the week has gone on, the choice facing lawmakers and businesses increasingly looks like this: Companies can get a 20 percent tax rate with substantially limitations on their deductions or they can get a rate around 22 percent without as many limitations.

“They can’t make the budget numbers work at a 20 percent rate. That’s why they are taking deductions away,” said Howard Wagner, a director in the National Tax Office of accounting firm Crowe Horwath.

Trump hinted over the weekend that the rate might have to go to 22 percent. The business community appears to be split on whether a lower rate or more deductions would be a better deal. Companies with a lot of physical assets and research like tech and manufacturing tend to want to keep the deductions. Financial firms that aren't as heavily reliant on debt and imports are advocating for the lower rate.

The Business Roundtable, which is currently chaired by JPMorgan Chase CEO Jamie Dimon, is pushing hard to keep the 20 percent rate.

“We obviously are enthusiastic about the 20 percent rate,” Joshua Bolten, president of the Business Roundtable, said on a call this week with reporters. “From the standpoint of investment in the United States, 20 percent is better than 21 percent, and 21 percent is better than 22 percent.”

The average business tax rate in major developed countries — the group the United States most directly competes with — is around 23 percent. Getting below that has been a key goal for Republicans and business executives.

“The most important thing is to get a bill in that 20 percent neighborhood,” said Neil Bradley, chief policy officer for the U.S. Chamber of Commerce, the largest business advocacy group. The Chamber has repeatedly pushed for the “lowest rate possible.”

But the No. 1 concern is getting a bill done. Bradley spent 20 years of his career on Capitol Hill and knows that it's going to take some dealmaking in the final stage of the process. He says there’s “no reason to have a straitjacket that might limit lawmakers’ ability to get to an agreement.”

A slightly higher corporate rate would also allow lawmakers to give more of a break to certain individuals who currently face tax hikes in the bill. Wealthy families in New York, Connecticut and California would lose the ability to deduct their state and local taxes, a substantial hit to some with big homes and large local tax bills.

Republican lawmakers are faced with trade-off as the House and Senate begin meeting to bridge their differences and come up with a final bill that can pass both chambers and get to the president's desk. There's outcry from individuals who say they'll have to pay more under the bills and there's outcry from the business community saying the tax cut meant to help them might not give much of a break after all.

Democrats say it's telling that Republicans are currently choosing between helping corporations or their donors more. Left-leaning economists remain skeptical that giving so much extra money to businesses will really help average workers.

Businesses “want their 20 percent rate and their loopholes,” says Joseph Stiglitz, a Nobel Prize-winning economist who was President Clinton's top economic adviser. “The loopholes mean that many will be paying less than 20 percent.”

But companies say if the tax bill is about creating more businesses and jobs in the United States, then lawmakers need to get the details right.

“The last minute includes of the corporate AMT was a real head scratcher. That needs to be fixed,” says Lehner of the Motor and Equipment Manufacturers Association.