Incumbent Democratic U.S. Sen. Mark Begich and his Republican opponent, Dan Sullivan, do not get along, and each has subjected the other to months of negative advertising.

But the relationship between Begich and the Libertarian candidate in the Senate race, Mark Fish, is considerably warmer, with Begich fighting to make sure Fish is included in debates, then tossing him softball questions that highlight their shared views on domestic spying.

Recently, Begich's campaign has even run radio commercials touting Fish's candidacy alongside his own -- meaning that since Fish hasn't spent any money to advertise his own campaign, Begich has now spent more money promoting Fish than Fish has himself.

"He likes my positions so well, I'm looking forward to an endorsement," Fish said in an interview Tuesday.

Begich's official position is that he wants third-party candidates like Fish to be heard.

"Since many of the debate hosts won't include Mr. Fish, Sen. Begich believes it is only fair to give Alaska voters all the information," Max Croes, Begich's communications director, said in an emailed statement.

But several observers say Begich's effort to boost Fish's profile is actually a shrewd act of electioneering -- one likely designed to drive shaky Sullivan supporters into Fish's column, and shaky Fish voters to Begich. The number of voters in the pool is small, but in a tight and costly election, the strategy makes sense, one local pollster said.

"I think Begich is playing a game where if he can shake half a percent off of Sullivan and onto Fish, it's half a percent that Sullivan hasn't got," said Ivan Moore, a local left-leaning pollster who isn't actively involved in the Senate race. "And that may well make the difference."

The strategy hinges on what Begich's campaign describes as a long list of positions that the Democrat shares with Fish. Those are laid out on a Begich campaign website that's being advertised on Facebook.

On issues like domestic surveillance and corporate personhood, the site highlights views common to Begich and Fish, and contrasts them with Sullivan's. And a new radio ad from Begich's campaign says that only two candidates oppose the Patriot Act and wiretapping by the National Security Agency.

"That's Mark Begich and Libertarian Mark Fish," a narrator says. "True Alaskans fighting the Dan Sullivan surveillance state."

Begich's campaign has also lobbied debate organizers to include Fish -- to the point where the Republican executive director of the Fairbanks Chamber of Commerce, Lisa Herbert, took to the opinion pages of the Fairbanks Daily News-Miner last week to complain that Begich had questioned the "motives and integrity" of her group, which left Fish out of a forum on Tuesday.

Sullivan's campaign has long held that Begich needs a viable third-party candidate in the race to draw votes away from Sullivan, arguing that Begich's base isn't big enough to win a head-to-head election in Alaska, where there are twice as many Republicans as Democrats.

In an August strategy memo, Sullivan's campaign manager Ben Sparks pointed out that when Begich was first elected to the Senate, in 2008, the Alaska Independence Party candidate, Bob Bird, drew 13,000 votes -- or more than three times Begich's margin of victory over incumbent Republican Ted Stevens.

"Mark Begich is using a third-party candidate as a political tool in a shameless attempt to try and bolster his own sinking campaign," a spokesman for Sullivan, Thomas Reiker, wrote in an emailed statement Tuesday. "But, Alaskans know better -- they know that a vote for a third-party candidate is a vote for Mark Begich."

The segment of Sullivan supporters who would contemplate switching to Fish amounts to a small group, said Moore, probably fewer than 2,000 votes in this year's election. Then, there's a separate set of voters inclined to vote for Fish who could potentially be shifted into Begich's camp.

In a poll Moore released Monday, Fish drew 4.5 percent, which would equate to about 12,000 votes in a typical non-presidential election year.

Targeting groups that small is rare, Moore said, but logical in this year's election, which has drawn some $50 million in spending, and about $9.5 million from Begich's campaign alone.

"This is a race like no other, where we start to see those things," Moore said.

However, a spokeswoman for the National Republican Senatorial Committee, Brook Hougesen, said in an email Tuesday that her group, which backs Republican Senate candidates across the country, hadn't seen similar tactics used anywhere else.

Fish said he found Begich's strategy "a bit disturbing" but added that his own views have been accurately represented by Begich, "so there's nothing really that I can say."

It remains unclear, however, how Begich's message will be received.

Daniel Hamm, the president of the Alaska Republican Assembly -- which brands itself the Republican wing of the Republican Party -- posted Begich's pro-Fish website on a conservative Facebook page on Tuesday, generating a long, diverse string of comments.

Hamm said in a phone interview that many conservatives are already angry with the Republican Party for "not being Republican enough" and don't need any encouragement to withhold their support from Sullivan.

"They're going to vote Libertarian or undeclared no matter what," Hamm said. "They're either going to vote for Mark Fish or write in George Washington or something."

Others, however, are less engaged, and Begich might sway a few people "who are in the middle," Hamm added.

As for the votes in Fish's column now, some might agree with Begich on civil liberties and surveillance. But Fish argued that Begich's vote for the Affordable Care Act could keep Libertarians from shifting to the Democratic ticket.

"No Libertarian would have voted for Obamacare," Fish said. "That is not compatible with Libertarianism in any sense of the word."

One of the commenters on Hamm's Facebook post, meanwhile, had his own unique take.

"Mark Fish is a good guy," said the commenter, Jeremy Thompson. "Unfortunately, Begich has captured some voters using Fish as bait. These folks will look into their nets after Nov. 4th and find them empty or full of large holes."