Senators are girding for the possibility that they may not know for days, or even weeks, which party will be in the majority next year. 

Close contests combined with record numbers of mail-in ballots could delay results in Senate battlegrounds. Races in Arizona, Iowa, Maine and North Carolina are expected to be extremely close, meaning a delayed result in any of those states might leave lawmakers in a state of limbo as they wait to find out who will control the Senate starting in January.

And it looks like one or both of the Senate races in Georgia are headed to a Jan. 5 runoff, which would take place the same week the Senate is expected to convene for the start of the 117th Congress.

A delayed determination of the majority party would likely dampen any early momentum for scrapping the Senate filibuster — a high priority for some liberal senators and allied outside groups — and could complicate negotiations on a coronavirus relief package in the lame-duck session.

Republicans control 53 seats and are expected to defeat Sen. Doug Jones (D) in Alabama, where President Trump is overwhelmingly popular. That means Democrats need to capture four Republican-held seats and the White House to win the majority, or five GOP-held seats if President Trump wins a second term.

“It’s all going to be so different this time with the counting of early ballots,” said a Senate Democratic aide. “I think it’s going to be very confusing, at least for a little while.”

Here are the states with races that could lead to delayed results.

Georgia 

Strategists and political handicappers expect one if not both of the Senate races in Georgia to require a Jan. 5 runoff. State law stipulates that a runoff election is needed if no candidate gets more than 50 percent of the vote on Election Day. 

The top two vote-getters would advance to the runoff, and that scenario is all but certain in the special election for Sen. Kelly Loeffler’s (R) seat, where there are 20 candidates in the race.

But it’s also looking like a real possibility in the race between Sen. David Perdue (R) and Democratic challenger Jon Ossoff. Recent polls show both candidates with less than 50 percent support.

“We are prepared to ensure all eligible votes are counted in this election and that we flip as many Senate seats as possible this cycle, including winning possible runoffs,” said Democratic Senatorial Campaign Committee spokesman Stewart Boss.

A Senate Republican strategist predicted a 49-49 split in the Senate after Election Day, with both GOP-held seats up for grabs on Jan. 5.

Maine 

Strategists in both parties are expecting possible delayed results in the race between Sen. Susan Collins (R) and state House Speaker Sara Gideon (D) — if neither candidate wins a majority of first-place votes, the state will use a ranked-choice process to determine the winner.

Rep. Jared Golden (D) wasn’t declared the winner in ranked-choice voting until 9 days after the 2018 midterm elections.

Recent polls show Gideon with a consistent but small lead over Collins, though neither candidate has been able to get over the 50 percent mark in recent weeks. 

“I don’t expect either Gideon or Collins to get over 50. That will take a few days,” said Kyle Kondik, the managing editor of Sabato’s Crystal Ball at University of Virginia’s Center for Politics, which handicaps races.

Arizona 

Early votes and absentee ballots cast a few days before Tuesday will be counted and their results made public shortly after polls close, but absentee ballots received on Monday and Tuesday will take a few days to tabulate.

Maricopa County Recorder Adrian Fontes told reporters that results of late-arriving ballots will be reported on Thursday or Friday, which means the winner of the Senate race might not be announced until later this week.

Sen. Kyrsten Sinema (D) wasn’t declared the winner of the 2018 Senate race until almost a week after Election Day.

Polls show incumbent Sen. Martha McSally (R) in a competitive race with Democrat Mark Kelly. An average of recent polls compiled by RealClearPolitics shows Kelly with an average lead of 5.7 percentage points, but McSally supporters argue the polls are undercounting the GOP senator’s support.

Iowa 

Voters in the Hawkeye State were required to have their ballots postmarked by Monday, and officials have to count mail-in ballots that arrive up until Nov. 9. That means the results of the state’s Senate race may not be finalized for days after the polls close, depending on how many ballots arrive after Election Day.

Mail-in ballots are expected to help boost Democrat Theresa Greenfield’s vote count compared to Sen. Joni Ernst (R-Iowa).

Trump and Ernst appeared to open up leads in the final days of the 2020 campaign. A respected Des Moines Register poll conducted Oct. 26-29 showed Trump leading Democratic nominee Joe Biden by 7 points and Ernst leading Greenfield by 4 points. 

But an Emerson poll conducted Oct. 29-30 showed Greenfield in the lead by 4 points.

Gary Grant, a Republican pollster based in Iowa, said voters are breaking late to Trump and Ernst and the winner of the Senate race will be known by Wednesday morning. 

“I think as we get closer to the election people are starting to be a little more honest” with pollsters, Grant said. 

“I think we’ll know here election night. Statewide, our auditors have been gearing up for this since early voting opened back in September. I think we’ll probably know who’s won by 11 p.m.,” he added.

North Carolina 

Ballots arriving up until Nov. 12 will be counted in North Carolina, which means if the race between Sen. Thom Tillis (R) and Democrat Cal Cunningham is as close as strategists think, it may take a few days to determine the winner.

The big variable is voter turnout and what percentage of the vote will be counted on Election Day. 

Polls show the Senate race within the margin of error. Cunningham has a slim 2.6 point lead, according to an average of polls compiled by RealClearPolitics.

Morgan Jackson, a Democratic strategist based in North Carolina, said the contest is “looking good” for Cunningham but acknowledges “it’s going to be a very close race.”

“Cal has led in every single public poll and he’s led in all of our private internal polls from 2 to 4 and some of the most recent say 5 [points],” he said.

“It’s all about turnout,” Jackson said. “The key number is 150,000 to 200,000. If you see Cal peak with early voting and absentees with a 150,000-or-above or 200,000-vote lead then that’s going to be a hard hole for [Tillis] to dig out of.”

Jackson said early voting is at record levels and the question “wracking everyone’s brains” is how many more votes are to be expected.

“How much bigger is the electorate?” he said.

Michigan 

It will likely take a few days after polls close to tally up the final results of the Michigan Senate race, where Sen. Gary Peters (D) is favored but which Republicans consider their best opportunity after Alabama to capture a Democratic seat.

Even though officials began tallying up absentee ballots on Monday, the winner might not be declared until Friday.

Polls show Peters leading by an average of 5 points, but the state is a top priority of the Trump campaign, and Republican strategists think GOP challenger John James could pull off an upset.

“Because everything is going to be so close, the likely scenario is it will be a few days into the week until we find out,” said a Senate Republican strategist. “Michigan is one I encourage you to watch because John James is running so far ahead of Trump.”

The strategist said an internal poll showed James closer to Peters than public polls indicate.

The Senate Leadership Fund, a super PAC allied with Senate Majority Leader Mitch McConnell (R-Ky.) has spent heavily in the state.

Alaska 

Democrats see the Alaska Senate race as a sleeper that could deliver a blow to Republicans.

Trump’s weak approval rating in the state has put independent Al Gross within striking distance of Sen. Dan Sullivan (R) in a race that was on very few strategists’ radars earlier this year. 

A New York Times/Siena College poll of likely Alaska voters conducted from Oct. 9-14 showed Trump leading Biden by only 6 points, 45 percent to 39 percent.

Early votes and absentee ballots cast by Oct. 29, as well as votes cast on Election Day, will be tallied by Wednesday morning. Early votes and absentee votes cast after Oct. 29 will start getting counted on Nov. 10. That means the winner might not be known until mid-November. 

Kondik, of the University of Virginia, said if the Senate race in Alaska turns out to be really close, Republican candidates are likely to fare poorly around the country.

Texas 

Sen. John Cornyn (R) is a favorite to win reelection, but if Trump loses to Biden in the Lone Star State, the Senate race could wind up being very close, strategists say.

A poll of registered and likely voters conducted Oct. 13-20 by the Dallas Morning News and the University of Texas at Tyler showed Biden leading Trump by 3 points, 48 percent to 45 percent. 

Absentee ballots can arrive by the end of Wednesday and still be counted, which means the eventual winner of the Senate race might need to wait a day or two before confidently celebrating.