The results of the runoff elections will determine which party controls the U.S. Senate -- and voters are nearly split on their preference, preliminary exit poll results show.

Forty-nine percent prefer Republican Party control, while 48% prefer control by the Democrats, based on the preliminary results.

The GOP needs either seat to retain control of the Senate, while the Democrats need both to win control.

Voters also were nearly split in their vote for president in the general election, based on the preliminary results -- suggesting that Democrats were holding their own in runoff turnout.

Voters in the race between Democrat Raphael Warnock and Republican Kelly Loeffler report having voted a dead-even 47%-47% Donald Trump-Joe Biden, preliminary results show. In the contest between Democrat Jon Ossoff and Republican David Perdue, it’s about the same -- 48%-47% Trump-Biden, based on preliminary results.

-ABC News' Gary Langer, Christine Filer and Steven Sparks

Polls across the state are closing as a flurry of advocates urge those who haven't voted and are still standing in line to stay past 7 p.m. and make sure their ballots are cast.

Georgia voters also had until 7 p.m. to return absentee ballots in drop boxes across the state.

A few polling precincts have gotten judicial extensions to be open past 7 p.m.: one in Gwinnett County, two in Columbia County, one in Tift County and two in Chatham County. There was also an accident near a polling place in Ware County that may lead to a judicial order extending poll closing time, said Gabriel Sterling, the state voting system implementation manager.

Sterling, in the most recent election update, described the day overall as "smooth voting, steady voting."

He said the state was getting reports of longer lines forming in Houston, Cherokee, Paulding and Forsyth counties with wait times approaching an hour, but not going over.

-ABC News' Quinn Scanlan

Former President Barack Obama tweeted to Georgia voters that while state polls close at 7 p.m., they should stay in line if they've arrived at their polling location in time.

"You have the right to vote, no matter how long it takes," Obama tweeted.

Some precincts in the state will be open past 7 p.m. due to court orders.

Obama joined a virtual rally for Democratic candidates Rev. Raphael Warnock and Jon Ossoff earlier this month and has appeared in digital ads for both candidates. On Monday, the former president tweeted "the stakes could not be higher" in promoting the runoff elections.

A majority of voters in Georgia's Senate runoffs think the presidential election was fair, preliminary exit poll results show.

More than half -- 56% -- of voters think the presidential election in Georgia was conducted fairly, while 41% do not, according to the preliminary results.

President-elect Joe Biden defeated President Donald Trump by nearly 12,000 votes in Georgia. Trump repeatedly has made unsubstantiated claims of voter fraud in Georgia, among other states.

Most voters also express at least some confidence in the current runoff elections. Seventy-three percent are very or somewhat confident that votes in the runoffs will be counted accurately, while 26% are not very or not at all confident, according to the preliminary results. This is down from a similar question in November, when 85% were very or somewhat confident that votes in their state would be counted accurately.

-ABC News' Gary Langer, Christine Filer and Steven Sparks

Warnock called his projected victory a "historic moment," saying he "can't wait" to be in the upper chamber of Congress "to represent the concerns of ordinary people."

"I'm deeply honored that the people of Georgia decided to place their faith in me and have decided to send me to represent their interests in Washington, D.C.," Warnock told ABC News Chief Anchor George Stephanopoulos in an interview Wednesday on "Good Morning America."

"Certainly, this is a historic moment and I'm just deeply grateful to be a vessel in a moment in which we're facing such large problems in our country," he added, "and I can't wait to get to the U.S. Senate to represent the concerns of ordinary people."

Warnock, a senior pastor of the Ebenezer Baptist Church in Atlanta, the former pulpit of the Rev. Martin Luther King Jr., is the first Black senator Georgia has elected and only the 11th Black senator elected in U.S. history.

"Georgia is in such an incredible place when you think about the arc of our history, we are sending an African-American pastor of Ebenezer Baptist church where Martin Luther King Jr. served," he said. "This is the reversal of the old southern strategy that sought to divide people. In this moment we've got to bring people together in order to do the hard work and I look forward to doing that."

When asked about his top priority for this year in the Senate, Warnock said -- as he has throughout his campaign -- that the country needs to get the coronavirus pandemic under control.

"Like so many Americans, as we witnessed the incredible death toll over 350,000 Americans lost lives, lost livelihoods, we need a national strategy that takes this virus seriously, that gets the vaccine distributed safely and efficiently," he said. "We've got to re-open our economy, get our kids safely back to school and we got to make sure that people know that they will have their health care, particularly in the middle of a pandemic."

-ABC News' Quinn Scanlan