The unusual three-way Alaska Senate race is essentially a dead heat between Sen. Lisa Murkowski, Republican nominee Joe Miller and Democrat Scott McAdams, according to a poll released Thursday by the Club for Growth, a conservative organization backing Miller.

Miller, a Fairbanks attorney, led Murkowski by a statistically insignificant 2 points, 33 percent to 31 percent. Murkowski is running a write-in campaign after narrowly losing the GOP primary to Miller. McAdams, the mayor of Sitka, registered 27 percent in the poll of 400 likely voters taken Friday and Saturday. It had a 4.9-point margin of error.

Also Thursday, the Club for Growth political action committee announced a drive to ask more than 1,500 Murkowski donors whether they would like their money back, given that she did not honor the results of the party’s primary. The club plans to contact Murkowski’s GOP contributors via mail to inform them that they can request a refund, similar to an effort the organization undertook after Sen. Arlen Specter (D-Pa.) left the GOP in April 2009.

The mailing will include a letter explaining Murkowski’s broken promise to support the Republican Party nominee and a letter addressed to the Murkowski campaign that donors can use to ask for their money back. Murkowski still had about $1 million in the bank after the primary campaign; third-quarter fundraising reports are due out Friday.

“Lisa Murkowski received this money running as a Republican, and now she’s running against the Republican,” Club for Growth President Chris Chocola said in a statement. “She promised to support the winner of the Republican Primary, then broke her word.”

Also according to the Club for Growth survey:

Miller’s “committed” support was 29 percent, compared with 22 percent committed to voting for Murkowski and 21 percent committed to McAdams.

McAdams led Murkowski 29 percent to 26 percent among 55- to 64-year-olds. However, Miller led among this demographic with 35 percent.

To account for Murkowski’s write-in candidacy, the poll asked respondents in rotating fashion who they would vote for, Miller “the Republican,” McAdams “the Democrat,” or “another candidate,” as Murkowski’s name will not be on the ballot. Voters must write in her name and fill in an oval next to the write-in space.