North Carolina Congressman G.K. Butterfield is one of a half-dozen federal lawmakers facing an ethics probe for allegedly pocketing portions of his taxpayer-funded travel stipend.

The investigation comes on the heels of calls for Butterfield, a Democrat representing the state’s 1st Congressional District, to return $4,000 in campaign donations from a political action committee of embattled Rep. Charlie Rangel, D-N.Y. Butterfield has declined to do so or recuse himself from an investigation by the House Committee on Standards of Official Conduct (aka the ethics committee) of Rangel. Butterfield is one of 10 members of that committee.

Congressmen receive daily allotments, called a per diem, for overseas travel. Because “foreign officials or U.S. ambassadors” often pick up the tab for federal lawmakers, members sometimes keep the difference, according to a report published Aug. 31 in The Wall Street Journal.

“Lawmakers routinely keep the extra funds or spend it on gifts, shopping or to cover their spouses’ travel expenses, according to dozens of current and former lawmakers,” the newspaper reported.

No system exists for lawmakers to return excess per diem funds to the government, the Journal reported, and investigators might conclude the standards need to be clarified.

E-mails to Butterfield’s press secretary were not returned this week, but the three-term Democrat told The Daily Reflector of Greenville that he would cooperate with the investigation.

“I have complied with the requests of [the Office of Congressional Ethics] and will comply with any other request from the ethics committee,” he said.

In January, Butterfield faced criticism for spending $4,406 for food and lodging at a five-star hotel while attending climate-change talks in Denmark. Butterfield said that lawmakers weren’t aware of the costs prior to the trip and that House leaders made the travel arrangements.

In response to the ethics investigation, Butterfield’s Republican opponent, Ashley Woolard, called on the congressman to resign.

“Citizens of the First District need honest leadership that will help our struggling economy, not another greedy politician feeding at the public trough as our economy burns,” Woolard said in a statement.

Also this week, a House panel dismissed ethics allegations against Butterfield’s fellow Democrat, Rep. Mel Watt of the 12th Congressional District. Investigators had questioned the timing of a fundraiser Watt held shortly before the House voted on financial regulatory reform legislation last year.

David N. Bass is an associate editor of Carolina Journal.