It could be days or weeks before one of the most divisive and closely-watched Senate races in the country is decided.
Write-ins captured about 41 percent of the vote with 99 percent of precincts reporting as of this morning.
Miller received 34 percent and McAdams had 24 percent of the vote, according to unofficial returns.
The write-in votes will have to be counted, and a declared winner could be weeks away.
The Alaska Division of Elections only counts the names of write-in candidates if they exceed names on the ballot or if the write-ins are within 0.5 percentage points of the leading candidate.
No Alaskan candidate for statewide office has won more than 27 percent in a write-in campaign, and nationally, only one U.S. Senator in history has been elected via a write-in campaign.
If Murkowski pulls off a win, it would not only be a historic win for her but a stunning defeat for former Alaska governor Sarah Palin, who campaigned vigorously against the incumbent senator.
Amid a record snow in Anchorage -- Alaska's largest city -- charges of voter intimidation by Miller, and Murkowski launching a last-minute push to get out the vote, the fate of the race now rests in the hands of Alaska voters.
On Tuesday night, Murkowski greeted a crowd of enthusiastic supporters who chanted "six more years" as she hugged her father, longtime Alaska senator and former Gov. Frank Murkowski, who was defeated by Sarah Palin.
"This is about our state," she said. "What do we do when they tell us we can't do something? We take it on!"
She acknowledged there was still a long way to go but said the race has brought together people from all parties and points of view to move Alaska's interests further.
Robert Campbell, Miller's campaign manager told the Associated Press Tuesday that initial results were disappointing but said "several teams including those with attorneys, would be on their way to Alaska for the ballot count."
The battle was bitter from the beginning and one that divided Republicans.
Endorsed by Sarah Palin and funded by the Tea Party Express, Miller defeated Murkowski in a primary that stunned the Republican establishment. But the incumbent, who has a longtime feud with Palin, didn't back down, despite calls from Republican leaders. She decided to wage a write-in campaign on the Republican ballot, as a result of which she was stripped off her post on the Republican leadership.
Both Murkowski and Miller pulled out all stops days before the election to boost their chances. Miller held a rally with Palin last Friday which also featured, albeit via video, former Arkansas Gov. Mike Huckabee, Rep. Michele Bachmann, R-Minn., and Sen. Jim DeMint, R-S.C.
Murkowski last week got a boost from the Alaska Supreme Court, which allowed the elections division to give voters a list of certified write-in candidates at the polls before they voted.
She even released a campaign ad featuring the late Sen. Ted Stevens, who recorded the endorsement just days before he died in a plane crash.