It’s primary election day in Texas, the first primary to be held in the country.

AUSTIN (CBSDFW.COM/AP) – Texas kicks off primary season ahead of the 2018 midterm election, with implications for Democrats and Republicans alike in an election year that could alter the direction of Congress and statehouses across country for the final two years of President Donald Trump’s term.

Today voters will chose which candidates will face-off on the ballot in November. These are runoff primaries. If no one wins the majority outright, the top two candidates move to a runoff election in May.

Things worth keeping an eye on Tuesday as Texans cast ballots:

DEMOCRATIC SURGE

Democrats remain underdogs to knock off Republican Sen. Ted Cruz and Republican Gov. Greg Abbott, but there’s been a surge among Democratic candidates and voters that reflects nationwide momentum for the left since Trump’s election.

There is at least one Democratic candidate in every congressional district — 36 of them — for the first time since 1992, the year of a national Republican wave. Democrats have 25 contested congressional primaries, and leading Senate candidate Beto O’Rourke raised $2.4 million in the final three months of 2017, more than Cruz’s $1.9 million haul.

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Registered Democrats also outnumbered Republicans in early voting in the most populous counties tracked by the state. Democrats cast more than 406,000 ballots compared to Republicans’ 353,000. In the 2014 midterm primaries, Republicans posted a 3-2 advantage in early voting.

“We have candidates everywhere, and that means we are reaching voters who haven’t heard from Democrats in a long time,” says Texas Democratic Chairman Gilberto Hinojosa. “That’s a good thing for November.”

GOP HOUSE DISTRICTS THAT WENT FOR CLINTON

Three Texas congressional seats — the the 32nd District in North Texas, the 7th District in metro Houston and the 23rd District from San Antonio across border country — are among the 23 Republican-held seats nationally that sided with Hillary Clinton over Trump in the 2016 presidential race.

Hoping to continue that trend are seven Democratic candidates on the ballot today vying to challenge Republican Pete Sessions, who has held the 32nd Congressional District seat for 15 years, in November. Some of those names include George Rodriguez, Ed Meier, Lillian Salerno, Brett Shipp and Colin Allred.

As a group, all the candidates have raised a lot of money — nearly $1.7 million through the end of 2017. Compare that amount with Sessions who raised more than $1.4 million through last year.

Democrats need to flip 24 GOP-seats to reclaim a majority in the U.S. House.

The Houston seat is likely headed to a runoff. The question is whether Moser, the liberal criticized by national Democrats, is among the two candidates. The San Antonio-border country seat could yield a runoff, as well, between Gina Ortiz Jones, an Air Force veteran, and Jay Hulings, a former federal prosecutor.

Jones’ backers include former Texas Senator and one-time gubernatorial candidate Wendy Davis and the pro-choice Democratic group Emily’s List. Hulings is backed by the No. 2 House Democrat, Steny Hoyer, along with fellow San Antonians Rep. Joaquin Castro and former Obama Cabinet member Julian Castro.

NASTY REPUBLICAN BATTLES

The Republican race between Angela Paxton and Phillip Huffines, for Texas Senate District 8, has been the most expensive and some say most bitter rivalry primary for state office.

Paxton, the wife of Attorney General Ken Paxton, Huffines, the twin brother of state Senator Don Huffines, have had dueling television ads attacking one another and claiming each is the right person to represent Collin County and part of northern Dallas County.

Huffines is the former Dallas County Republican Party chairman, who emphasizes his background as a businessman – his family is in the car selling business. As a teacher, Paxton says education is among her top priorities and calls herself a constitutional conservative.

District 8 is largely Republican, so analysts think whoever wins the primary will become the new state senator.

TRUMP EFFECT

The president won Texas during the 2016 nominating process and in the November election. Now he’s a central figure in midterm primaries.

George P. Bush, nephew of fellow Texan and former President George W. Bush, touts endorsement from Trump and his son Donald Trump Jr. as the younger Bush seeks re-election as land commissioner. Congressional candidates across the state pledge fealty to the president and blast his critics.

It’s most obvious in crowded Republican primaries for safe GOP seats opened by incumbents retiring. Kathaleen Wall, who is running a southeast Texas seat now held by Rep. Ted Poe, is an example. One of her 30-second ads alternates between images of Trump and Wall, while a voiceover offers attributes of the two: “Successful businessman man. Successful businesswoman. … Talks tough (Trump). Aims tough (Wall, wielding a rifle). Loudly strong (Trump). Quietly strong (Wall). Great hair (Trump). Greater hair (Wall).”

There are 21 contested GOP House primaries.

NATIONAL DEMOCRATS VS. LIBERAL GROUPS

It’s not uncommon for the Democrats’ House campaign arm to have favorites in a primary, but they stepped beyond that recently, openly criticizing a Democratic hopeful in a Houston-area seat held by Republican John Culberson.

In a memo posted online, the Democratic Congressional Campaign Committee called Laura Moser a “Washington insider” and blasted her comments published in a 2014 Washingtonian magazine article. Moser said she’d “rather have her teeth pulled out” than live in Paris, Texas. Party aides say the comments would be used by Republicans to make Moser unelectable in the 7th Congressional District, but their intervention has miffed Texas Democrats, including some of her opponents.

Liberal groups also have cried foul. Moser is running to the left of other leading candidates, and Our Revolution, Sen. Bernie Sanders’ political organization, endorsed her in the wake of the DCCC memo.

The battle is sure to intensify if Moser qualifies for an expected runoff.

BETO O’ROURKE vs. TED CRUZ

O’Rourke and Cruz aren’t on the same Senate ballot yet, but the primary will be the first test of their standing ahead of their almost certain Senate matchup in November.

The Democratic congressman outraised the Republican senator in the last quarter of 2017 and has touted his candidacy’s grassroots appeal for Texas Democrats who haven’t had much to cheer about lately. Cruz, who has nominal primary opposition himself, isn’t taking the race lightly, however. The senator also is using his stature with endorsements in several of the 21 contested Republican House primaries.

While it’s not any absolute harbinger of November, it will be worth checking O’Rourke’s vote totals compared to Cruz’s to see what kind of gap exists ahead of their fall campaign.

LOSING LEADERSHIP

Texas has eight sitting House members who are not seeking re-election, meaning the state with the second-largest delegation will be losing some key experience and leadership in Washington from its Republican majority.

The outgoing lawmakers include Sam Johnson, the 87-year-old Vietnam veteran and member of the House Ways and Means Committee; Jeb Hensarling, 60, who chairs the House Financial Services Committee; Lamar Smith, 69, who heads the House Science, Space and Technology Committee; and Poe, who has been in Congress since 2005.

Each of them hails from solidly Republican districts, but they could be replaced by even more conservative nominees. Both Hensarling and Smith were being term-limited out of their chairmanships but were well positioned to continue exerting veteran House influence had they stayed.

The polls are open until 7 p.m. click here to get your precinct number and find your polling location.

(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)