By John S. McClenahen With U.S. Commerce Secretary Donald Evans headed home to Texas following his resignation, speculation in Washington, D.C., is centered on Mercer Reynolds III, a Cincinnati business executive who was finance chairman of President George W. Bush's re-election campaign, as his replacement. But the larger question is how influential will he be. At least publicly, Evans seemed to be chief economic cheerleader for the Bush White House, with U.S. Trade Representative Robert B. Zoellick, among others, taking the lead roles in developing the details. Indeed the trade representative's office will be a focus of activity early in Bush's second term. The president's trade negotiating authority, known as Trade Promotion Authority, is set to expire June 1, 2005, and next year Congress has an opportunity to vote on whether the U.S. remains a member of the Geneva-based World Trade Organization.