Updated

The issue of nepotism entered the arena within minutes of the start of a U.S. Senate debate here Tuesday night between Republican incumbent Lisa Murkowski (search) and Democratic challenger Tony Knowles (search).

"I did not make nepotism an issue," Knowles said. "Frank Murkowski (search) did when he appointed his daughter."

Knowles was referring to Murkowski's 2002 appointment of his daughter when he vacated his Senate seat to become governor. The issue has continued to haunt her, but she said she's asking voters to judge her by her performance. At the same time, she has not tried to avoid the topic of how she got the job, she said.

"I have not asked Alaskans to accept that or get over that," Murkowski said.

A week before Tuesday's election, the two are virtually tied, according to polls from their own campaigns. It's a race being watched nationally as Republicans strive to keep their slight majority in the Senate, which hasn't seated an Alaska Democrat in more than two decades.

During the debate, Murkowski, 47, also got an opportunity to address a potential weakness facing her 61-year-old rival — his age. She said their age difference and her two-year head start in the Senate gives her an edge.

"By the time I am the same age as my opponent I'll have 16 years of seniority," Murkowski said. "That does make a difference."

Knowles shot back: "If age is an issue, I'm pretty young considering the average age in the Senate."

Most of the hour-long debate, however, touched on a wide range of less-personal topics, from oil drilling in the Arctic National Wildlife Refuge and building a natural gas pipeline in Alaska to the war in Iraq, gun control, affordable health care and stem cell research. Both support ANWR development, building a gas pipeline and additional funding to ensure the protection of troops in battle.

Near the conclusion of the debate, moderator John Tracy asked the candidates which team they supported in the World Series — the Boston Red Sox or the St. Louis Cardinals.

"Sox," Murkowski said.

"Sox," Knowles said.

The candidates wrapped up their relatively polite exchange with a quick summary of why they should go to Capitol Hill.

"We need a positive change. The status quo is not good enough," Knowles said. "I'm asking for the privilege of serving, not to serve the privileged."

Murkowski said the current congressional delegation — three Republicans — should stay in place to continue pursuing drilling in the refuge, construction of a gas pipeline and other crucial issues for Alaska.

"The team we have in Washington is not a status quo team," she said. "It's a team that delivered for the state of Alaska for years."

Earlier Tuesday, four of the other five candidates in the race complained about being left out of debates in the final week before the election.

Jim Sykes of the Green Party, Scott Kohlhaas of the Libertarian Party and nonpartisans Marc Millican and Ted Gianoutsos appeared at a news conference, saying a full debate would better serve Alaska voters.

According to the latest elections data, more than 52 percent of the state's 469,042 voters are registered as independents or nonpartisans. Republicans and Democrats together represent slightly more than 40 percent of the electorate.

"Alaskans deserve better," Kohlhaas said. "The qualified candidates for U.S. Senate deserve to be heard equally."

Tuesday's debate was held at the University of Alaska Anchorage. An NBC affiliate, KTUU-TV in Anchorage, was among the sponsors. Tracy, the moderator and a station news anchor, told debate viewers the other five candidates would be addressed in a later news cast.

Another debate is scheduled for Thursday night, sponsored by the Anchorage Daily News and KAKM, a public TV station in Anchorage.