Republican Gov. John Hoeven's Democratic opponent believes Hoeven should disclose whether he'll serve out his third term if voters re-elect him, speculating that the governor may seek a U.S. Senate seat.

Tim Mathern, a Fargo state senator, promised Wednesday to limit himself to two terms as governor if he is elected. He said he believes that is enough for anyone, and he would support a constitutional amendment to limit the governor to two terms in office.

"I believe in two terms, you can accomplish your goals for your administration. And if you haven't in those eight years, it is time you turned that administration over to somebody else," Mathern said. "The time has come to develop new leadership."

This fall's election "is probably the closest, and first, message that we're going to get from the people about whether or not they really want somebody to serve (as governor) more than eight years," Mathern said. "I think they're going to decide that eight years is enough."

This fall, Hoeven and Lt. Gov. Jack Dalrymple are attempting to become the first North Dakota ticket to be elected to three four-year terms.

Hoeven brushed off Mathern's statements, saying he is concentrating on his current job and his re-election campaign. "That's what I'm focused on," he said. "I'm excited about the future of the state."

Hoeven has not ruled out seeking another office while he is serving as governor, although he has passed on opportunities to do so. During his last re-election bid, Democrats speculated that Hoeven would run against Sen. Kent Conrad, D-N.D., in 2006. He did not.

Sen. Byron Dorgan, D-N.D., is up for re-election in 2010, which would be the midpoint of Hoeven's third term if he is re-elected.

Mathern and his running mate, Rep. Merle Boucher, D-Rolette, are longtime incumbents who are themselves in the middle of four-year legislative terms. Mathern was first elected to the Senate in 1986, while Boucher won his House seat in 1990.

Don Larson, Hoeven's campaign manager, said he found it "ironic that Tim Mathern is even asking this question, when he himself is running for another office in the middle of his Senate term. In fact, his running mate is also in the middle of his term."

Mathern said a governor failing to serve out his term is more significant than a state legislator seeking another office.