The 2020 elections will feature a broad field of Democratic and Republican candidates in a fight that will determine control of Texas.

Monday was the last day candidates could file for the March 3 primaries, the prelude to the much-anticipated general election featuring President Donald Trump’s reelection bid, high-profile congressional races in Texas and a rumble for control of the Texas House.

With former U.S. Housing secretary and former San Antonio mayor Julián Castro struggling to gain traction in most Democratic presidential polls, former Vice President Joe Biden, Sen. Elizabeth Warren of Massachusetts or Sen. Bernie Sanders of Vermont will look to capitalize in Castro’s home state.

With a half-dozen Republicans retiring from Congress and a handful of others facing stiff challenges, Texas will also be an active battleground in the bigger tussle for control of the U.S. House in 2020.

But the most intense drama is expected to involve the Texas House. Democrats need nine seats to take control and have targeted at least 22 occupied by Republicans, who are trying to reclaim the 12 seats they lost in 2018. Much of the action will be in races in Dallas, Tarrant, Collin and Denton counties.

Here are some highlights from the races:

U.S. Senate

A large field of Democrats is vying for the nomination to challenge Republican incumbent Sen. John Cornyn.

In the run-up to the filing deadline, polls revealed that Democrats were not thrilled with their choices. Five major candidates were all below 20% of those surveyed, indicating a close but uninspiring contest.

Democrats had hoped that former Rep. Beto O’Rourke of El Paso or Castro would get into the race. But O’Rourke opted against running, while Castro continued his bid for president.

With them out of the mix, one of the top contenders could emerge as a viable threat to Cornyn.

“You’ve got a crew of candidates that have been running hard for several months and they are ready for this,” said Ed Espinoza, executive director of the liberal group called Progress Texas. “Now that the field is set, you won’t have people taking a wait-and-see approach. People can start picking their teams, giving money and getting a closer look at the candidates.”

The major Democratic candidates are former U.S. Rep. Chris Bell of Houston, Houston council member Amanda Edwards, former Air Force helicopter pilot MJ Hegar of Round Rock, activist Cristina Tzintzún Ramirez of Austin and state Sen. Royce West of Dallas.

In the GOP primary, Cornyn faces several opponents, including Dallas businessman Mark Yancey.

Bell, 60, served one term in Congress before losing his seat in 2004 amid a redistricting battle. The progressive Democrat was the party’s 2006 nominee for governor against Rick Perry.

Edwards, a 37-year-old Houston lawyer, is in her first term as an at-large council member representing more than 2.3 million people. She’s considered a rising star in the Democratic Party but must build her name recognition outside of Houston.

Hegar, 43, narrowly lost a 2018 congressional race to incumbent Republican Rep. John Carter of Round Rock. She opted to run for Senate instead of a rematch against Carter, describing herself as the fighter Democrats needed to beat Cornyn.

Tzintzún Ramirez, 37, is a Chicana/Mexican American organizer who co-founded the Workers Defense Project and founded the Hispanic advocacy group called Jolt. She’s also worked to mobilize immigrant communities and hopes to use her organizational skills to get more people of color and younger voters to the polls.

West, 67, has served in the Texas Senate since 1993, where his focus has been on improving public education and criminal justice reform. The Dallas lawyer was instrumental in the University of North Texas putting a campus in southern Dallas, as well as a law school downtown. He’s considered one of the most influential politicians in North Texas.

Other notable candidates in the Democratic Party contest include activist Sema Hernandez of Pasadena, who got 24% of the vote in the 2018 Senate primary O’Rourke won, and Adrian Ocegueda of Flower Mound, who works in private equity.

Quick takes from filing day

Congress

Turnover in the Texas delegation has been extraordinary in the Trump era.

Of 25 Republicans in the House at 2021 inauguration, only 11, at most, will still be in office when the next president is sworn in. Democrats flipped two seats in the midterm elections. A half-dozen senior Republicans decided not to seek reelection -- a mass departure that reflects the party’s long odds of reclaiming the majority it lost last year.

That “Texodus,” as Democrats have dubbed it, has set the table for an especially lively campaign season.

District 24

In this Dallas-area district, Rep. Kenny Marchant, R-Coppell, is calling it quits after eight terms and a near-miss last year, when he survived a challenge from Democrat Jan McDowell by just 3 points.

Five Republicans are running, including former Irving mayor Beth Van Duyne, who served more than two years as regional administrator of the federal Department of Housing and Urban Development. She resigned from that post in August to run for Congress.

McDowell faces a half-dozen other Democrats vying for the seat, including Kim Olson, the party’s 2018 nominee for state agriculture commissioner and a retired Air Force colonel; Candace Valenzuela, a Carrollton-Farmers Branch school board member.

District 32

Republicans are hoping to reclaim the Dallas seat captured last year by freshman Rep. Colin Allred. The former pro football player and attorney ousted 11-term congressman Pete Sessions, a longtime member of the House GOP leadership team.

Dallas businesswoman Genevieve Collins faces former Navy SEAL Floyd McLendon Jr. and three others in the GOP primary.

Collins has raised nearly a half-million dollars, a solid sum though just a third of the incumbent’s war chest.

District 17

Sessions is trying to make a comeback.

But instead of seeking a rematch against Allred, he has turned his sights on a safe GOP seat being vacated by Rep. Bill Flores, R-Bryan. The district stretches to Waco, Sessions’ childhood home, and where his father served as a federal judge before his tenure as FBI director.

Flores was unhappy about Sessions’ move.

“He lived there half a century ago,” Flores said in a recent interview. “Look at the definition of a carpetbagger and make your own determination. … We've got a lot of really good emerging leaders in District 17. And they deserve a chance to be the next congressman or congresswoman from this district before Pete does. This district is not Dallas.”

Eleven Republicans are seeking the seat.

District 22

In suburban Houston, Pierce Bush became the latest member of the Bush dynasty to try his luck in politics, jumping into the race to replace retiring GOP Rep. Pete Olson.

Bush is the CEO of Big Brothers Big Sisters Lone Star, and grandson of the late President George H.W. Bush. He father, Neil Bush, is brother to former President George W. Bush of Dallas. His first cousin, George P. Bush – son of former Florida Gov. Jeb Bush – is the Texas land commissioner.

By Monday afternoon, 14 Republican candidates had filed.

Sri Kulkarni, who fell short by 5 percentage points last year against Olson, is favored to win the Democratic nomination.

District 21

Democrats are eager to topple freshman GOP Rep. Chip Roy of Austin, a former chief of staff to Sen. Ted Cruz, in a district that runs from the state capital to San Antonio. The front-runner in that primary is Wendy Davis, a former state senator from Fort Worth who lost the 2014 governor’s race to incumbent Greg Abbott. She rose to fame with a filibuster of a strict anti-abortion bill.

District 13

In the Texas Panhandle, where former House Armed Services Chairman Mac Thornberry, R-Clarendon, is retiring after 13 terms, former White House physician Ronny Jackson filed Monday for one of the most reliably Republican seats in the country.

Chris Ekstrom, a businessman who has vowed to be a “relentless ally of President Trump” and “the most conservative member of Congress,” sarcastically welcomed Jackson to the fray by noting that President Barack Obama had called him a “‘dedicated and valuable member’ of his team during his failed administration,” and one who had his “complete trust.”

Jackson is one of 14 Republicans chasing that nomination. He recently retired from the Navy as a rear admiral and began serving as White House physician in 2006 under George W. Bush. He continued in that role through the Obama administration and until his resignation last year after Trump picked him to run the Department of Veterans Affairs.

Jackson pulled out amid allegations that he had been abusive to coworkers as head of the White House medical unit, was not careful enough with prescriptions, and occasionally drank on duty — all of which he denied.

District 11

Another West Texas vacancy in a safely Republican seat. Eleven Republicans are vying to replace former Agriculture Chairman Mike Conaway, R-Midland.

District 28

In Laredo, Rep. Henry Cuellar, the Democrat with the most pro-Republican voting record in the House, faces a challenge from the left in the primary. Activist Jessica Cisneros is backed by progressive luminaries including Sen. Elizabeth Warren, a presidential candidate, and New York Rep. Alexandria Ocasio-Cortez.

District 23

One of the most competitive districts in the country, this vast West Texas prize came open when three-term Rep. Will Hurd, R-San Antonio, decided to call it quits.

Hurd edged past Democrat Gina Ortiz Jones by just 689 votes last year. The Iraq war veteran conceded two weeks after Election Day.

Jones is one of five Democrats and nine Republicans seeking the seat.

Texas Legislature

In the Texas House, both parties are raising millions of dollars to fight for control.

Gov. Greg Abbott has said he’s going to help Republican House hopefuls, along with new PACs that are emerging because of the vacuum created by last summer’s scandal that forced Angleton GOP Speaker Dennis Bonnen to announce he’ll retire by January 2021.

Southlake Rep. Gio Capriglione is part of a Republican PAC called Lead Texas Forward that aims to raise $5 million for GOP candidates in order to fill a void left by the sidelined Bonnen. Capriglione said he could see the battle for the Texas House costing as much as $75 million, which increases the need for the fundraising.

“We are planning every single day to go and raise that money. The reality is it’s a different deal than it was two years ago,” he said. “That election from two years ago told us that we needed to start earlier, that we can’t just take any of this for granted.”

Austin Rep. Celia Israel, who leads the House Democratic Campaign Committee, declined to specify how much her committee and allied groups such as labor, Planned Parenthood and Annie’s List will raise.

“Generally, we talk in millions and millions,” she said. “We don’t know what the number is. We’ve never been in this kind of political juxtaposition before — you know, presidential year, redistricting, high energy. We know that’s going to translate into millions of dollars.”

Democrats say they are targeting as many as 22 seats currently held by Republicans. In each of those Texas House districts last year, U.S. Sen. Ted Cruz or his Democratic challenger Beto O’Rourke prevailed by a single-digit margin, explained state Democratic Party executive director Manny Garcia.

“There's a few others that we are keeping an eye on as well,” he said. “But safe to say 22 [that were] within single digits” in the 2018 U.S. Senate race are in play.

Republicans can be expected to challenge freshmen Democrats in all 12 House seats they lost last year – meaning as many as 34 of the chamber’s 150 seats could be up for grabs.

As many as half of the battleground districts will be in North Texas, experts say.

In Dallas County, Republican Morgan Meyer won his district by only 220 votes in 2018 and has drawn three Democratic challengers. Angie Chen Button, the other Republican in Dallas County, will face a rematch against Brandy K. Chambers, who she edged out by just a little more than 1,100 votes.

Democrats are also hopeful about their candidates in traditionally conservative counties like Collin and Tarrant, where they are targeting five districts.

In Collin, Rep. Matt Shaheen won his last election by only 400 votes and Rep. Jeff Leach won by less than 2,000. Perhaps seeing hope in those results, multiple Democrats have jumped into each of those races this year.

In Tarrant, Democrats will look to get over the hump in House District 92, in which they were within 3 percentage points of beating Republican incumbent Jonathan Stickland, who failed to get 50% of the vote in the district. Stickland, a polarizing figure even among Republicans, has said he will not seek re-election and it is unclear whether his retirement will make the Democrats’ task easier or harder.

Recent growth by groups like Tarrant Together, an organization focused on voter registration and identifying Democratic candidates, has given Democrats reason for hope. But Republicans are eager to show that despite Democratic gains in 2018, Tarrant remains a red county.

Democrats will also have to play defense in some of the seats they picked up last year. Freshmen Democrat Michelle Beckley surprised many when she upset incumbent Republican Ron Simmons in Denton County. This year, she’ll have to get past primary challenger Paige Dixon before she can defend her seat against Republicans in the general election. Two candidates, Kronda Thimesch and Nancy Cline, have filed as GOP challengers.

The five Dallas Democrats who flipped Republican seats will also be high on the GOP’s target list. Former State Rep. Linda Koop, who was upset by Democrat Ana-Maria Ramos, is seeking to take back her North Dallas County seat. But she’ll have to get by attorney Rick Walker in the primary before she can set her sight on Ramos.

Republican Luisa Del Rosal will look to make the case that her district is center-right as she tries to unseat freshmen Democrat John Turner. Turner won his seat during a marquee year for Democrats, when a far-right challenger, Lisa Luby Ryan, unseated the Republican centrist incumbent, Jason Villalba.