Former U.S. Sen. Mark Begich, under pressure from some in his party to withdraw from the Alaska governor's race, said Tuesday that he isn't dropping out.

"Let me make it very clear to the reporters and others: If you want to talk about the process, talk to someone else," he told press and a crowd of cheering supporters at his campaign headquarters in Anchorage. "We are done with that. I'm in the race to win. It's a three-way race, so get used to it."

The Democrat's announcement came about 90 minutes before the state's deadline to withdraw from the Nov. 6 general election.

Begich is facing off against incumbent Gov. Bill Walker, an independent, and former state Sen. Mike Dunleavy, a Republican. Some Democrats have said they're concerned Begich and Walker will split the vote, resulting in a Dunleavy win. Walker is a Republican-turned-independent, who is running again this year with his Lt. Gov. Byron Mallott, a Democrat.

In a statement Tuesday, Walker said no matter how many candidates are in the governor's race, the election will come down to decisions made on the Permanent Fund and fiscal plan. He described those decisions as tough and ones that "party politicians would like to run away from."

The Dunleavy campaign also used the announcement to further its messaging, referring to Walker and Mallott as a "failed experiment" and Begich as a "career politician" in a statement.

The candidates for Alaska's governor will vie for votes in a state where about 57 percent of registered voters are nonpartisan or undeclared, according to numbers from the Alaska Division of Elections. About 25 percent of the state's 567,403 registered voters are registered as Republicans, and about 13 percent are registered as Democrats.

"I don't think any rigid analysis of politics is going to help describe what's going to happen in the next 60 days," said Alaska Republican Party chairman Tuckerman Babcock. "I think, partly after this primary, it's a little presumptuous for anyone to say, 'this is how this is gonna come down.' … Alaskan elections are always so unique."

Another candidate, Libertarian William "Billy" Toien, is also running for governor.

A petition on MoveOn.org calling for Begich to drop out of the race had about 900 signatures by Tuesday, on top of the original 100 it had when it was posted online last month. The original signers included Alaska Native corporation executives, current and former lawmakers, members of Walker's administration, and others.

Tuesday by 5 p.m. was the deadline for candidates to withdraw from the Nov. 6 general election. If a candidate drops out between that deadline and the general election, their name will still appear on the ballot because it will have already been printed, but votes for them won't be counted, said Division of Elections spokeswoman Samantha Miller.

Dunleavy has a better chance of winning in a three-way race than a two-way race, but he's not the "automatic winner," said Ivan Moore, a longtime Alaska pollster who has done polling work for both Begich and Walker.