Huge U.S. corporations are forming lobbying groups to try to influence what could become the hottest congressional debate over comprehensive tax reform in a generation.

The newest organization calls itself the Tax Reform Coalition. Backed by companies including American Express and Xerox, it filed paperwork with Congress last week to register as a lobbying group.

The coalition's registration suggests it will have a broad portfolio, lobbying on "issues related to corporate tax reform," but no one involved would answer questions on Friday.

It joins an increasingly crowded playing field of lobbying groups and politicians strategizing for what Washington will look like in 2013 following national elections in November 2012.

Another lobbying group, the RATE Coalition, was formed in October and pushes for a cut in the 35 percent tax rate on corporate profits.

WIN America Campaign, a third group, has been advocating since March for a tax holiday for profits that U.S. companies made overseas. Its supporters include multinationals and Washington's largest business lobbying group, the U.S. Chamber of Commerce.

John Buckley, a tax professor at Georgetown University Law Center, said that during the most recent major U.S. tax overhaul in 1986, businesses formed a large coalition to support it.

"They were able to shape it," Buckley said, and "that's what people want to do now."

The uptick in lobbying activity follows a proposal two months ago by U.S. Representative Dave Camp, chairman of the tax-writing House Ways and Means Committee. Camp, a Republican from Michigan, said he wants a lower corporate rate, an exemption for overseas profits and other changes.

Campaign Issue

Republican hopefuls in the race for the November 2012 presidential election have put forward tax proposals with similar ideas, launching speculation that 2013 may be a defining year in Congress for U.S. tax policy.

Companies are choosing to organize now.

"There's a lot of risk in waiting to weigh in on something like tax reform," said Clint Stretch, managing principal of tax policy at Deloitte Tax.

"You're going to see more and more companies trying to figure out how to have a voice" in the tax debate, he said.

Four large U.S. companies are listed as the backers of the Tax Reform Coalition: American Express, Intel , Tupperware Brands and Xerox. They have hired a former lawyer on the Ways and Means Committee as one of their lobbyists.

It was not immediately clear how much the organizations will work together.

The RATE Coalition is larger than the newer Tax Reform Coalition. It claims 25 member companies, with Intel a member of both groups. While it urges a cut in the corporate rate, it is agnostic on other changes.

WIN America is even more narrowly focused on the issue known as repatriation. U.S. companies must pay tax on earnings abroad when they bring the money home, minus a credit for foreign tax paid, and many have chosen to leave their profits elsewhere even if the money sits nearly idle.

Spokeswomen for the RATE Coalition and WIN America said they were not aware of the newest group.

Coordination or Competition?

By forming broad alliances, companies are able to pull together research, consulting staffs and other resources, said Jim McCrery, a former Republican congressman who now lobbies for WIN America and others.

"They're able to marshal their resources in a coordinated fashion," said McCrery, a partner at Capitol Counsel.

Corporate groups face an especially skeptical audience in congressional Democrats. Representative Sander Levin, D.-Mich., of the Ways and Means Committee has said that some of the ideas under discussion would cause a further shift in the tax burden from the wealthy to the middle class.

President Barack Obama has criticized the idea of cutting taxes on U.S. companies' operations abroad.

But the prospect of a historic change means companies are preparing to have their say.

"There's lots of people that have their hand in this, as one would expect. When you're talking about rewriting the Internal Revenue Code, that tends to get people's attention," said Kenneth Kies, managing director of the Federal Policy Group.