WASHINGTON — Agriculture Secretary Tom Vilsack declined Thursday to endorse a far-reaching House bill to curb greenhouse gas emissions. An Oklahoma congressman said it would "destroy” farmers’ livelihoods. Rep. Frank Lucas, R-Cheyenne, repeatedly pressed Vilsack at a hearing to take a stand on the bill. At one point, he asked Vilsack, the former governor of Iowa, whether he would vote for it if he were a congressman representing Iowa. Vilsack didn’t answer the question directly. He said it was up to lawmakers to write the bill and that more work could be done to improve it. But Lucas, the top Republican on the House Agriculture Committee, said House Democratic leaders weren’t allowing any more work to be done on the bill and that they may bring it up for a vote later this month. "The cap-and-trade part of the bill creates a national energy tax that will do more harm to production agriculture, American industry and our standard of living than it will do any good for the environment,” Lucas said. The legislation would place a national cap on carbon emissions and use a market-based system of credits to enforce the caps. Companies with more credits than they needed could trade credits to other companies unable to meet their emissions caps. Rep. Collin Peterson, D-Minn., the chairman of the Agriculture Committee, voiced the concerns many farm-state lawmakers have about the system, saying that the U.S. Department of Agriculture should be tasked with overseeing how farms are regulated under the cap-and-trade regime. Peterson also said he didn’t think the bill could get through Congress in its current form, in part because of the opposition from rural lawmakers.