LINCOLN, Neb. — Nebraska political campaigns are trying to lock in as many early votes as possible in the weeks before next month’s election as county officials prepare to launch early in-person voting.

Voters have already started returning absentee ballots in the mail, and leaders of some of the state’s major campaigns are intensifying their push with a flurry of phone calls and mailings.

Lancaster County Elections Commission Dave Shively said his office has already received requests from campaigns and political parties for lists of voters who have requested but not yet returned an absentee ballot. His office started mailing ballots on Oct. 3 and has already seen some returned. Lancaster County will allow in-person voting starting Monday, but other county offices may be closed to observe Columbus Day.

Nearly 208,000 Nebraska voters cast an early ballot in the 2012 presidential election, accounting for more than one-quarter of the roughly 804,000 votes, according to the secretary of state’s office.

Shively said early voting has consistently grown since 1996, when lawmakers eliminated the requirement that voters provide a reason why they wanted to cast an early ballot. Lancaster County saw 5,300 residents request an absentee ballot in 1996, compared to more than 33,000 for the last presidential election in 2012, he said.

Shively said he expects “somewhere in the neighborhood of 35,000” absentee requests this year, and many people have asked about early in-person voting.

“Some people may winter in Arizona or Texas and want to get it taken care of before they leave,” he said. “Some just want to get it over with.”

Nebraskans for the Death Penalty is planning to release a series of new campaign mailings on Monday and will urge supporters to vote early, said spokesman Chris Peterson. The postcards seek to reduce confusion by making clear that voters who want to keep the death penalty should vote to “repeal” the state law that abolished it.

Peterson said his group’s internal polling has consistently shown strong support for the death penalty in all areas of the state, including Omaha and Lincoln. In addition, he said death penalty opponents could try to launch a last-minute ad blitz or make a surprise announcement to try to sway public opinion.

“So yes, we want more people to vote early,” Peterson said. “We believe it’s to our advantage.”

Death penalty opponents are also encouraging their backers to vote early and are helping those who express interest in doing so, said Dan Parsons, a spokesman for the Retain a Just Nebraska campaign. Parsons said volunteers are speaking to voters in church services, coffee shop gatherings and through phone calls.

“We’ve got a very passionate volunteer base,” he said.

In Omaha’s contested 2nd Congressional District, campaign staffers for Democratic U.S. Rep. Brad Ashford are making roughly 5,000 calls a day, encouraging supporters to vote by mail. Campaign workers are focusing on voters who have received absentee ballots but haven’t yet turned them in, said campaign manager Sam Barrett.

“It’s very important” for the campaign, Barrett said. “Who knows what can pop up on Election Day. Your kid could be sick or you may not feel well. Voting by mail is easy and you can do it on your couch, in your PJs, watching football.”

Volunteers for Ashord’s challenger, Don Bacon, have been contacting residents who have voted early in the past to make their case for the Republican candidate.

“It’s something that we, like every campaign, take seriously,” said Mark Dreiling, Bacon’s spokesman. “Campaigns have to work hard for every vote, and now that people are voting earlier, campaigns have to reach out earlier.”