By David Lawder

WASHINGTON, March 31 (Reuters) - That marching sound in Washington on Monday was the pounding of shoe leather out of lobbyists' offices to do battle over the Treasury Department's proposed overhaul of financial regulation.

Trade groups, financial services companies, lawmakers and even regulatory agencies slated for the chopping block moved to protect their turf as the Treasury rolled out its vision for the biggest regulatory revamp since at least the Great Depression.

Treasury Secretary Henry Paulson knows change won't come easily or quickly, and is leaving the most controversial parts of the plan to the next administration to take up.

"These long-term ideas require thoughtful discussion and will not be resolved this month or even this year," he said in introducing a plan that would would combine a patchwork of federal financial regulators into three super agencies over an eight-year period.

Among the first victims among regulatory agencies would be the Commodity Futures Trading Commission, which would be swallowed up by the Securities and Exchange Commission.

The Treasury argues that complex and risky financial products have taken over futures exchanges and need common scrutiny as securities.

But farm interests in Congress said the proposal could hurt agricultural markets and promised it would face an uphill battle.

Walt Lukken, the CFTC's acting chairman, said some specialized expertise may be "jeopardized" in the merger.