At least 50,000 ballots remain to be counted that could affect margins and possibly outcomes in two closely watched political races in Alaska.

The competition for Democratic Sen. Mark Begich's U.S. Senate seat has drawn national attention, with Republican candidate Dan Sullivan holding a 8,149-vote lead over Begich -- a 3.6 percent difference -- after the first round of vote counting immediately following Tuesday's general election.

The governor's race is also tight, with independent Bill Walker leading Republican Gov. Sean Parnell by 3,165 votes, or just 1.4 percent.

More than 220,000 votes have been counted in those contests. To make sure the remaining ballots are properly verified, campaigns have sent observers to watch teams sort through absentee and questioned ballots at the state Department of Elections' regional headquarters in Anchorage, Fairbanks, Wasilla, Juneau and Nome.

Tyson Gallagher, an observer and data director for Gov. Sean Parnell's re-election effort, said Republican candidates typically gain ground at this stage in the process. But it's uncertain if that will occur this time, he said.

"This has been a funny year all in all, so who knows what will happen," said Gallagher, standing outside the rooms where the reviewing took place Monday in Anchorage.

One monkey wrench is an unknown number of ballots that were cast early at some 200 absentee in-person voting locations around the state. More than half of those sites were established in villages for the first time this year, in rural regions that may skew in favor of Walker and Begich. Those ballots numbered about 5,200 on Friday.

The bulk of those ballots, which are considered "absentee" and not "early" votes, have already reached regional offices, said Gail Fenumiai, Elections director.

Others may not arrive for days. She said there is no "drop-dead date" for those ballots to arrive, but said they would all be counted.

"That's the only mystery number out there," she said.

"I hate using the word 'mystery,'" she added. "There is accountability in the process."

The division did not track the number of ballots cast by early voters at those locations, because doing so would have meant checking in with each of the 200 sites daily before the Nov. 4 election, she said.

The counting on Tuesday is expected to begin as early as 9 a.m. in some regional headquarters but won't start until 1 p.m. in Anchorage, officials said. A third round of counting is planned to start Friday.

Fenumiai said that as of Monday night the division had tallied 34,884 absentee ballots to be counted, as well as 2,651 early votes.

"Early" voting officially takes place only at regional offices, where voter eligibility can be validated on the spot, said Fenumiai. Though people can cast votes early around the state, it's not considered "early" if the ballot must be sent in to regional offices before its eligibility can be determined, she said.

"The language is confusing," she said.

Additionally, 13,038 questioned ballots -- typically consisting of votes cast at the wrong polling place -- remain.

And the number of ballots to be counted is still expected to grow: 10,512 absentee ballots sent out to potential voters had not yet been returned as of Monday night.

On Monday afternoon, Fenumiai said she wasn't certain what would be counted on Tuesday. "It will be ALL the remaining early votes plus some of the full count absentee and some question ballots," she said in an email.

Randy Ruedrich, former chair of the Alaska Republican Party, was at the regional elections headquarters in Anchorage on Monday monitoring the ballot review for some Republican candidates. He said the process was going smoothly and that the two-person review teams were doing a thorough job of confirming voter information.

Karen Gillis was helping oversee a team of observers for the Walker campaign. "There are no surprises and nothing that's raising our eyebrows," she said.