Despite serious efforts from all corners to unseat Alaska Sen. Lisa Murkowski, new statewide polling for Alaska Dispatch News shows her with a sizeable lead.

In a statewide survey of 660 registered voters between Sept. 28 and Oct. 2, Murkowski led with 50 percent of those polled. Conservative Libertarian candidate Joe Miller came in a distant second with 18 percent, followed by Democrat Ray Metcalfe with 12 percent, independent Margaret Stock with 7 percent and 2 percent choosing another candidate. Eleven percent were undecided.

The poll was conducted for Alaska Dispatch News by Alaska Survey Research with live questioners via cellphones and landlines. The margin of error is 3.8 percent.

Since the survey was taken, Murkowski made news by joining Alaska Sen. Dan Sullivan and some three dozen Republican members of Congress in denouncing GOP presidential nominee Donald Trump. Murkowski has long wavered on whether to support Trump, saying in recent months that she had not yet made up her mind about voting for him and raising objections to some of his racist and sexist statements.

On Saturday, Murkowski called for Trump to step down from the ticket after a video emerged in which he bragged in vulgar terms about groping women.

"When I believe somebody is not fit for office, I have to speak up," Murkowski told Alaska Dispatch News.

It is unclear how the tape will affect the presidential race in Alaska, where Trump holds a slim lead and Clinton is deeply unpopular. And it is unclear if walking away from her party's top candidate will hurt Murkowski in her race. Enthusiasm for Trump has been low among Alaska's Republican Party leaders but fervent among his followers.

Murkowski would have to take a big tumble to be at risk given recent polling, and support would have to coalesce around a second candidate, while her opposition is currently spread across three other candidates.

In 2010, Murkowski won the election with 39 percent of the vote with a write-in campaign, after she lost the Republican primary to Joe Miller. Miller drew 35 percent of the vote and Democrat Scott McAdams took home 23 percent.

The Alaska Survey Research poll found support for Murkowski was spread evenly across regions of Alaska.

Miller, running as a Libertarian this year, saw his highest levels of support in Southcentral Alaska and Fairbanks, according to the poll.

The poll also found support for Murkowski across party lines. Of those who claim no party, she was leading with 48.5 percent of those polled. Her support among registered Republicans was at 64.3 percent and she pulled voter support from 32.4 percent of registered Democrats.

Miller's largest base of support came from registered Republicans (24 percent), while only 17 percent of non-affiliated Alaskans said they plan to vote for him.

Just more than half of Alaska's 522,757 registered voters were registered as nonpartisan or undeclared as of Monday, according to the Division of Elections.

Challengers on the left — Democrat Ray Metcalfe (a former Republican legislator and anti-corruption activist) and independent Margaret Stock (also a former Republican but a staunch Trump opponent with some more left-of-center positions) — aren't doing great.

Metcalfe polled at 12 percent, with most of his support coming from Democrats. Despite his winning the August primary, Alaska's Democratic party has all but shunned its Senate candidate. Interior Democrats recently voted to endorse Stock instead, and former Democratic Sen. Mark Begich said recently that he's supporting the independent candidate as well.

In the poll, Metcalfe only drew support from 31 percent of registered Democrats. Their votes were otherwise split between Murkowski (32 percent) and Stock (20 percent). More than half didn't recognize Metcalfe's name.

Overall, Stock was polling in the no-chance-to-win range: 7 percent.

That's largely due to a lack of name recognition: Nearly three of four voters polled did not know who she is.

Murkowski's favorability ratings were good in the new poll, with 52 percent of those questioned having a "very positive" or "somewhat positive" opinion of her. Only 28 percent of those questioned had a negative opinion.

Murkowski's highest positive rating — 61 percent — came from those who described their political ideology as "moderate."

Murkowski's campaign released polling with similar results on Friday, in a survey of 500 likely voters taken Oct. 5-6. The poll, by Moore Information of Portland, showed Murkowski in the lead with 49 percent and Miller at 16 percent, Metcalfe at 9 percent, Stock at 8 percent and independent Breck Craig at 1 percent. Fifteen percent of voters were undecided in that poll.

The ADN poll talked only with registered voters and not likely voters. Who shows up at the polls on Election Day will matter, though age-related demographics don't appear to result in much difference in the U.S. Senate race.

Murkowski leads across all ages of the poll respondents, and by significant margins.

Her largest leads come in the 35-44 and 45-54 age ranges, with 55 percent and 57 percent of respondents, respectively.