"Fault lines" in each political party have to be dealt with before tax reform can be completed, the chairman of the House Ways and Means Subcommittee on Tax Policy told CNBC on Thursday.
For Republicans, the divide is over whether to make the reforms temporary or permanent, said Rep. Peter Roskam.
"Permanent is paid for, permanent is harder — but permanent is better," he said in a "Squawk Box" interview.
Roskam said some Democrats see the economy as a zero-sum game — "a fixed pie — and if somebody does better, someone else is doing worse."
"I don't buy that. I don't think that's how the economy works," he said.
The six-term Illinois Republican also emphasized the "urgency" surrounding the issue, saying Congress has a rare possibility to enact permanent tax reform. Not since the 1920s has the Republican Party had this level of control over the White House and both chambers of Congress.
"Not delivering on tax reform is completely unacceptable," he said. "We have a once-in-a-generation opportunity to have fundamental tax reform, and let's drive as hard as we possibly can to get that done."
Roskam said legislation may not end up at the 15 percent corporate tax rate that President Donald Trump has predicted. Rather, the congressman said his blueprint proposed a 20 percent corporate rate and reducing the seven current individual rates to three.
"This is a matter of negotiation," Roskam said, adding that his committee is working toward four goals: growth, simplicity, dealing with base erosion and making reform permanent.
Of the polarization in Congress and the increasingly rare display of bipartisanship, Roskam said those issues have to be put aside.
"Both political parties have some sorting out to do, and there's an urgency to this," he said.
Correction: Rep. Peter Roskam is chairman of the House Ways and Means Subcommittee on Tax Policy. An earlier version misstated his title.