Alaska Senate-Treadwell

Alaska Lt. Gov. Mead Treadwell is shown Thursday, Sept. 12, 2013, is shown as he launched his U.S. Senate campaign. Republicans could have a bruising primary in August 2014 before ahead of the general election battle with U.S. Sen. Mark Begich, D-Alaska. (AP Photo/Mark Thiessen)

ANCHORAGE, Alaska - The Republican field for U.S. Senate grew by one, or possibly two, on Thursday.

Alaska Lt. Gov. Mead Treadwell officially launched his campaign at a rally with supporters at his headquarters in Anchorage.

The launch came as the governor's office announced the resignation of Natural Resources Commissioner Dan Sullivan; there has been speculation that Sullivan, too, will seek the Republican nomination for Senate. Sullivan was traveling Thursday and unavailable for comment.

Treadwell told reporters after his speech that he hadn't heard from Sullivan about the resignation. But Treadwell said he looked forward to being in the race with Sullivan, a former assistant U.S. Secretary of State, if he runs.

"He's helped me navigate Washington, and I've helped him navigate Alaska," Treadwell said. "I think it's important to know Alaska, and I have the experience that we have here, and we'll take the campaign on the issues."

Also in the Republican race is Joe Miller, a tea party favorite who upset incumbent U.S. Sen. Lisa Murkowski, R-Alaska, in the 2010 GOP primary only to lose to her after she mounted a write-in campaign to win the general election.

Treadwell said the GOP focus has to be on beating U.S. Sen. Mark Begich, D-Alaska, and not tearing other Republicans apart in a bruising primary.

"We can't have a demolition derby in the Republican primary, we've got to beat Mark Begich in November," he said.

When asked about Miller, Treadwell said his strategy is "to tell the truth." Miller isn't "the only guy who stands up for liberty. He's not the only guy who is standing up for life," Treadwell said.

There was no mention of the problems at the state GOP leadership level, where two Ron Paul supporters have been ousted as chairmen in the last year by moderate members of the party.

During the speech, Treadwell was surrounded by mainstream members of the Alaska Republican Party, receiving endorsements from former state House Speaker Gail Phillips, and former state Senate President Drue Pearce. Pearce later served as federal pipeline coordinator until being asked to resign when President Barack Obama took office. Treadwell's campaign co-chairs are former University of Alaska President Mark Hamilton, who didn't attend because he was moose hunting, and retired Marine Col. Catkin Burton.

Democrats predicted a tough fight among the GOP candidates.

"There is only one candidate in the race for United States Senate who has a proven record of fighting for Alaska families and small businesses, creating new jobs, protecting our military, and making progress on Arctic development - and that is Mark Begich," Alaska Democratic Party Chair Mike Wenstrup said in a statement. "It is going to be a long, contentious year for Joe Miller, Mead Treadwell, and Dan Sullivan - and we still don't even know what Sarah Palin will do."

Palin, a former Alaska governor and 2008 Republican vice presidential candidate, told Fox News last month she wasn't planning to run but indicated that she was keeping her options open.

Treadwell didn't mention any Republican rivals during a 15-minute speech to supporters, sounding as if his only opponent was Begich.

"In 2008, Ted Stevens didn't get justice and neither did we," Treadwell said. "We got Mark Begich and Obamacare, and it's time to fix that."

A jury convicted Stevens on Oct. 27, 2008, of seven felony counts of lying on Senate financial disclosure documents, and he lost to Begich eight days later. The conviction was dismissed in April 2009 because of prosecutorial misconduct. Stevens died in a plane crash on Aug. 9, 2010.

Treadwell said he is anti-abortion, would support repealing the federal health care overhaul and backs gun rights. He repeated the populist theme that Alaska could help lead the nation in oil and gas development if only the federal government would get out of the way.