Sen. Mark Warner, D-Va., hinted Thursday that the so-called Volcker Rule would be addressed in a more scaled-down version in legislation or merely through the existing regulatory structure.

Appearing on the cable network CNBC, Warner said an outright ban to stop commercial banks from proprietary trading, private-equity and hedge fund investments, as called for by President Obama, is too difficult.

"I think there is a recognition, within normal prudential regulation for these large financial firms, you need to take a special look at proprietary trading activities, the private-equity activities, making sure we don't commingle too many of these functions," he said. "But to have an outright ban — that gets to be a much more challenging proposition."

Warner is working with Sen. Bob Corker, R-Tenn., on the resolution and systemic risk portion of the Senate's financial reform legislation. He would not rule out including the proposal in the bill yet.

"It's still under discussion, but I think there's ways we can get this issue Chairman [Paul] Volcker has addressed into the mix, but there are clearly problems in terms of where you put the definitions in these areas and can you do it within the existing prudential regulatory structure," he said.

Last month, Obama asked lawmakers to update financial reform to include a ban on banking companies from proprietary trading and from working with hedge funds or private-equity firms.

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