Sen. Lisa Murkowski, running as a write-in candidate after losing the September GOP primary, has taken a narrow lead in the unusual three-way Alaska Senate race, according to public and internal polling monitored by the various campaigns.

Republican nominee Joe Miller appears to have slipped to third place, behind Sitka Mayor Scott McAdams. That order is reinforced by the National Republican Senatorial Committee’s decision to launch its first independent expenditure ad targeting the Democrat. The spot is the NRSC’s second on statewide television in two weeks and comes on the heels of Miller revealing that he was disciplined during his tenure as a local government lawyer for using a municipal computer for political purposes and attempting to cover it up.

The Alaska Supreme Court’s decision late Wednesday to allow the state Division of Elections to provide a list of certified write-in candidates to voters at polling places is an additional blow to Miller and a boost to Murkowski, given the difficulty of pulling off a successful write-in campaign. The state Supreme Court’s ruling overturned a lower court decision that had barred the Division of Elections from making the list of write-in candidates available.

“He’s slipping for sure,” a knowledgeable Republican operative said of Miller. “The Alaska Supreme Court ruling allowing voters to ask for a write-in ballot further sets him back. I still believe, as do most folks, that he will win — but just barely. If the write-in weren’t so confusing, he would probably not win.”

A Hays Research Group poll out Thursday showed McAdams at 29 percent and Miller at 23 percent. The category that led the poll with 34 percent was “write-in candidate,” which presumably means voters who support Murkowski. The poll, which did not include a screen for likely voters, was taken Monday and Tuesday.