But Mumpower also had a brush with potential ethics trouble early in his career when he and three other northeastern Tennessee lawmakers flew to Nashville aboard a plane chartered by a King Pharmaceuticals Inc. official to urge the state to buy more of the drugmaker's products.
Mumpower, who is a public relations executive from Bristol, maintains today he did nothing wrong by trying to promote the interests of one of his district's largest employers.
Republicans won a one-seat majority in the House in November, and have nominated Mumpower as their candidate for speaker when the Legislature convenes next month.
Republicans have interpreted their election success as a mandate to clean up the culture of the chamber that has long been dominated by West Tennessee Democrats.
Dick Williams of Common Cause, a group that advocates for stronger ethics and open government, said he hopes Mumpower and his fellow House Republicans live up to their promises of making the chamber more transparent and more ethical.
"I would hope their rhetoric over the past several years would put them in a position that they really do need to practice what they preach," he said.
Mumpower, 35, had a direct hand in crafting the state's sweeping new ethics laws after lawmakers threatened to deadlock over the issue during a special legislative session in 2006.
"It was one of the key moments in my career, I'm proud of it," Mumpower said in a recent interview with The Associated Press.
The special session was called in the aftermath of the FBI's Tennessee Waltz corruption sting that ultimately led to the conviction of five former lawmakers.
"It hopefully brings that whole chapter in Tennessee to an end," Mumpower said. "I resent still the legislators who took bribes, because it sullied their name and they paid for it, but it sullied everybody else's name by association."
The measure created the Tennessee Ethics Commission, limited cash campaign contributions to $50 and prevented former lawmakers and other state officials from working as lobbyists for 12 months after leaving the state.
But Mumpower's version of the bill was criticized by some lawmakers because it didn't include a $25,000 cap on aggregate campaign contributions, and because it allows lawmakers to accept up to $50 in free food and drink from companies that lobby the Legislature.
Mumpower said he believes that campaign finance restrictions infringe on First Amendment rights, and that "wining and dining" has decreased significantly since the law was passed.
Williams said Mumpower's compromise bill achieved many important changes, but came at the expense of public input because the agreement was hammered out behind closed doors.
"It truncated the public discussion of the issues," Williams said.
In 1999, Mumpower, current state Senate Speaker Ron Ramsey of Blountville and two other Republican lawmakers drew unwanted attention to themselves for flying to Nashville with King Pharmaceuticals' governmental affairs director, former state Sen. Jim Holcomb.
Peggy Williams, who was then executive director of the state Registry of Election Finance, said at the time that companies that employ lobbyists were prohibited from providing air transportation or gifts to lawmakers.
But it turned out that Holcomb had not been officially registered to lobby for King when the trip took place. Holcomb later paid a $25 lobbyist registration fee, and the Registry dropped its investigation. No action was taken against the lawmakers who took the free flights.
While Mumpower told the Kingsport Times-News in 1999 that he considered Holcomb an "advocate" for the company, he added he didn't know whether he was lobbying. Either way, Mumpower maintained then as now that he didn't do anything wrong.
"I don't think anything we did was out of line with what was allowed," he said in the AP interview. "I'm not going to apologize for doing something to help a major employer in my district."
Holcomb denies he was lobbying on that trip and wrote in a recent e-mail exchange that he only registered as a lobbyist because he was told the investigation wouldn't cease until he did.
"I was told that the issue would not be acquitted until I registered," he said.