Texas is home to the first primary races of the 2018 election and both parties will watch the results for indications of how the battle to control Congress may play out in November.
Republicans and Democrats alike are heavily invested in the outcome for both House and Senate races.
In the Senate contest, incumbent GOP Sen. Ted Cruz will face Democratic Rep. Beto O'Rourke.
Cruz was out with an attack against his opponent shortly after the Associated Press called the contest for each man.
In the most-watched House contest of the night, Democrats interfered in their own primary in the 7th Congressional District, which Hillary Clinton won in 2016 and Democrats hope to take from GOP Rep. John Culberson in November. The Democratic Congressional Campaign Committee — which usually attacks Republicans — criticized Democratic candidate Laura Moser for an essay she wrote that allegedly criticized living in Texas.
Observers will be watching how Moser does when results come in tonight.
She is one of 50 women running for a seat in Congress in bids to represent the Lone Star state.
Meanwhile, President Trump has tweeted his support for Republicans running in the Lone Star state and encouraged get-out-the-vote efforts.
Polls closed at 8 p.m. ET. Please keep checking back for updates.
10:55 a.m. - Turnout, female candidates, top spenders lose big
As the dust settles from Tuesday night's results in Texas, it's clear that enthusiasm on both the Democratic and Republican side was on display.
Democratic turnout topped 1 million votes for the first time since 2002, and reached levels not seen in the state since 1994. Republicans also set a record for turnout, passing their previous high set in 2010.
Female candidates also dominated the ballot last night. According to current results from the Texas Secretary of State's office, 26 female congressional candidates will either capture a nomination outright or advance to a runoff election in May: 24 of those candidates are Democrats, while just two are Republicans.
While many of those Democratic candidates are running in deep red districts not likely to flip in November, the sheer size of last night's "pink wave" is an indicator that 2018 is poised to be a watershed year for women running for, and winning, public office in America.
Last night also proved that money does not always translate into votes.
In Texas' 2nd Congressional District, GOP activist and donor Kathaleen Wall is in danger of missing a runoff election, even after pouring more than $6 million of her own money into her campaign. With 100 percent of precincts reporting in the district, Wall trailed the second place finisher Dan Crenshaw by more than 100 votes.
In a number of other congressional races, candidates that led the pack in fundraising also fell short.
Tahir Javed in Texas' 29th Congressional District, Alex Triantaphyllis in Texas' 7th Congressional District and Ed Meier in Texas' 32nd Congressional District both proved to be prolific fundraisers, but failed to make even a runoff election.
1:43 a.m. - Fletcher and Moser headed to a runoff in Texas 7th Congressional District
The Associated Press has projected that Democrats Laura Moser and Lizzie Pannill Fletcher will advance to a runoff election for the Democratic nomination on May 22 in Texas' 7th Congressional District.
Moser celebrated the result earlier tonight in a tweet.
The result also ensures more awkwardness for national Democrats and the Democratic Congressional Campaign Committee (DCCC), which now must decide if it wants to continue its campaign against Moser.
11:52 p.m. ET - Race to replace retiring Rep. Barton goes to a runoff
The Associated Press has projected that Ronald Wright, an ex-aide to Rep. Joe Barton, and former Navy combat pilot Jake Ellzey will proceed to a runoff election in May in Texas' 6th Congressional District to determine the Republican nominee in the race.
Barton announced his retirement last year following almost 30 years in Congress after admitting to sending inappropriate text messages to a woman.
11:48 p.m. ET - Trump has perfect win record in Texas primaries
President Trump has a perfect win record in tonight’s Texas primaries.
All the GOP candidates he tweeted about will win their Republican primaries with enough of a vote to avoid a runoff on May 22, according to Texas election returns.
The president last week tweeted his endorsement of Gov. Greg Abbott, Sen. Ted Cruz, Lt. Gov. Dan Patrick, Attorney General Ken Paxton, Land Commissioner George P. Bush, Agriculture Commissioner Sid Miller, Comptroller Glenn Hegar, and Railroad Commissioner Christi Craddick.
Here are his two tweets from Feb. 27:
11:22 p.m. ET - Texas 7th Congressional District in waiting mode
"Let the nail biting begin,” Texas 7th Congressional District candidate Laura Moser tweeted out shortly after the polls closed at 8 p.m. ET.
And then the waiting began. And went on. And on...
At her watch party in Houston, a young volunteer said goodbye in an attempt to get some sleep before his college exam tomorrow and another volunteer complained she can’t see the election results because she’s “too old.”
Just shy of midnight, with 40 percent of the precincts reporting, neither Moser nor Lizzie Pannill Fletcher had the 50 percent of votes needed to avoid a runoff.
Fletcher, who's been endorsed by EMILY's List and the Houston Chronicle, started her election day voting with her husband. After the polls closed, she tweeted her thanks to her supporters.
Meanwhile, Moser joked with supporters at her party that her team crafted a victory email response and one for if she's defeated. “We are going to make it to the runoff,” she said. “We are going to win the runoff because we have the best grassroots campaigns, organizers and message."
The National Republican Campaign Committee put out a statement criticizing Democrats for their interference in the primary and referenced the party's push for Hillary Clinton over Bernie Sanders in 2016.
"I guess the DCCC can't rig a primary as well as their counterparts at the DNC," NRCC communications director Matt Gorman said.
Moser has been confronted with a series of challenges during her campaign. She’s not only running as a Democrat in a district that has been held by Republicans for the last 50 years, she also has had to compete against several other Democratic candidates in the state’s primary. To top it off, she has had to respond to opposition from her own party after the Democratic Congressional Campaign Committee (DCCC) released negative research about her two weeks ago.
11:16 p.m. ET - Texas likely to elect first Latinas to Congress
The Associated Press has projected that former county judge Veronica Escobar has won the Democratic primary in Texas' 16th Congressional District to succeed Rep. Beto O'Rourke, who is running for U.S. Senate.
If she wins the general election in November, Escobar would be the first Hispanic woman from Texas ever elected to Congress.
State Sen. Sylvia Garcia also captured the Democratic nomination in Texas' 29th Congressional District to succeed retiring Rep. Gene Green, according to the AP, meaning Texas may end up sending two Hispanic women to Congress in 2018.
10:53 p.m. ET — George P. Bush wins Texas Land Commissioner nomination
Texas Land Commissioner George P. Bush declared himself the winner of his GOP primary and the Associated Press had called the contest for him.
"Texas voters - THANK YOU! Your steadfast support through this primary is what has made tonight’s victory possible!," he wrote.
Bush, son of former Florida Gov. Jeb Bush, faced a tough GOP primary where there were questions as to whether he would garner the more than 50 percent necessary to avoid a May runoff. He managed to do that and is favored to win in November.
In the closing days of the campaign, he heavily touted President Trump's endorsement of him.
10:39 p.m. ET - Cruz attacks O'Rourke's name in new radio ad
Sen. Ted Cruz released a radio ad against his Democratic opponent, Rep. Beto O’Rourke, that attacks the candidate for his name.
O'Rourke, whose birth name is Robert Francis, goes by “Beto,” which has Latino roots.
The ad, set to the tune of Alabama’s “If You’re Gonna Play in Texas,” includes the lyrics:
Liberal Robert wanted to fit in. So he changed his name to Beto. And hid it with a grin.
The early attacks were seen by political observers that Cruz is worried about his opponent, even though a Democrat hasn't won statewide in Texas since 1994.
O’Rourke outraised Cruz in fundraising by more than $1.5 million since January, according to FEC data. Since the beginning of the year, O'Rourke has raised nearly $2.6 million to Cruz’s $895,276.
10:11 p.m. ET - Van Taylor to be GOP nominee in retiring Rep. Johnson's seat
State Sen. Van Taylor has won the GOP nomination for retiring Rep. Sam Johnson's seat, according to an AP project.
Taylor was endorsed by the conservative group Club for Growth and, given the 3rd Congressional District's Republican bent, is widely expected to win in the general election.
9:14 p.m. ET - Gov. Abbott wins GOP gubernatorial nomination
Incumbent Gov. Greg Abbott won the Republican nomination for governor, according to an Associated Press projection.
The Democratic primary has not yet been called. There are nine total candidates running.
Abbott is the heavy favorite to win in November.
9:09 p.m. ET — Texas Senate race set: Cruz vs. O'Rouke
Incumbent Republican Sen. Ted Cruz will face off against Democratic Rep. Beto O'Rourke in Texas' U.S. Senate race this November, the Associated Press projects.
O'Rourke has out-fundraised Cruz since the beginning of 2018, and Democrats are banking on the 45 year-old as the man who can take down one of the conservative movement's most prominent figures.
Cruz put out a statement blasting O'Rourke as a "left-wing, liberal Democrat" who "is running as a vocal proponent of amnesty and open borders."
In addition to hitting O'Rourke on immigration, which is huge issue in Texas, Cruz also criticized O'Rourke for not supporting second amendment rights, another important issue in the gun-friendly state.
"Congressman O'Rourke is a vocal proponent of gun control and restricting the Second Amendment rights of law abiding citizens. That is a policy position embraced by Chuck Schumer and Elizabeth Warren, but it’s not a position that reflects the values of Texans. Texans want to see violent criminals prosecuted and incarcerated, but at the same time, Texans want to see our fundamental rights, including our individual right to keep and bear arms, protected," he said in the statement.
Cruz is hosting an election night event in Texas and O'Rourke will be hosting a Facebook Live event at 9:15pm EST to talk about tonight's results.
7:50 PM ET - Polls close in 10 minutes
With polls in Texas closing at 8 p.m. ET, the candidates are tweeting reminders to voters to vote.
Democrat Laura Moser, who is running for Congress in Texas' 7th Congressional District, reminded voters that as long as they are in line by closing time, they can vote:
And Democratic gubernatorial candidate Lupe Valdez had a similar reminder:
5:30 PM ET - Races we're watching
Here are some of the primary contests in Texas ABC News is watching closely:
4:15 PM ET - A pink wave?
2018 is proving to be a record year in the number of women running for political office.
More than 50 women are running for Congress in Texas alone. Of the state's 36 congressional representatives, only three are women and that could change come November.
3:52 PM ET - Democrats hopeful early voting tallies continue on Election Day
The first primaries of the 2018 election take place today in Texas.
Throughout the 11 days of early voting, Democrats cast at least 44,000 more ballots than Republicans in the biggest 15 counties, a trend the party hopes continues through Election Day.
High voting numbers would indicate Democrats are strongly motivated to get to the polls this year, which is a good sign for the party's hopes to retake control of at least one chamber of Congress.
Polls close at 8 p.m. ET. Check back through the day and night for more updates.
ABC News' Rachel Scott, John Verhovek, and Soorin Kim contributed to this report.