Super Tuesday contests will be critical in the race for the the Democratic presidential nomination. But there are also plenty of primaries further down the ballot that will provide clues about the battle for Congress in 2020.

Voters will head to the polls in 14 states and one territory Tuesday, and five of those states will be holding congressional primaries: Alabama, Arkansas, California, North Carolina and Texas. All but Arkansas are House and Senate battlegrounds in 2020.

Many of the congressional primaries may not be resolved Tuesday, however. It could be days or weeks before votes are fully counted in California because mail-in ballots can be postmarked on Election Day. The state has a unique top-two primary system where all candidates compete on the same ballot and the top two vote-getters, regardless of party, advance to November. Primaries may also be unresolved in Texas and Alabama, both of which have provisions where the top two candidates advance to a primary runoff if no one wins a majority of the vote. Runoffs in Alabama would take place March 31, while Texas contests would be May 26.

Here are seven dynamics to watch as the results roll in:

1. Incumbents in trouble?

Two House members from Texas are facing competitive primaries: Democrat Henry Cuellar and Republican Kay Granger.

Cuellar faces civil rights lawyer Jessica Cisneros, who once interned for him and has the backing of a slew of progressive groups and high-profile Democrats, including presidential hopefuls Bernie Sanders and Elizabeth Warren and New York Rep. Alexandria Ocasio-Cortez. Cuellar is considered one of the few Democrats opposed to abortion rights left in Congress.

Cuellar says he reflects his district, which is heavily Hispanic and socially conservative. Cisneros says that’s not the case. Though Donald Trump won Texas by 9 points in 2016, Hillary Clinton carried Cuellar’s 28th District by 20 points. Inside Elections with Nathan L. Gonzales rates the general election there Solid Democratic.

Outside money has poured into the race, with a group affiliated with EMILY’s List spending more than $1.2 million against the congressman. Cuellar, meanwhile, has received support from Democratic leaders, including Speaker Nancy Pelosi, but also from some groups that have typically backed Republicans, such as the U.S. Chamber of Commerce and Americans for Prosperity Action.

Outside groups have also been spending in Granger’s primary in the 12th District, which includes Fort Worth. The anti-tax Club for Growth is backing her primary challenger, former tech executive Chris Putnam, who has been critical of her role in government spending. Club for Growth Action and an allied PAC have spent more than $2.2 million combined against Granger.

The longtime congresswoman has gotten some help from Winning for Women Action Fund and the Congressional Leadership Fund, which have spent nearly $1.4 million combined.

Trump has endorsed Granger in the race, raising questions about whether a tea party-style challenge still works in today’s Republican Party. Inside Elections rates the general election Solid Republican.

Another incumbent to keep an eye on is California Democratic Rep. Jim Costa, a member of the fiscally conservative Blue Dog Coalition whose campaign has spent more than $829,000 on his primary. His chief Democratic rival is Fresno City Councilmember Esmerelda Soria.

2. Familiar faces

Super Tuesday primaries also feature a few familiar faces, including former lawmakers and high-profile politicians. Trump’s former attorney general, Jeff Sessions, is running for his old Senate seat in Alabama, which is one of Republicans’ best pickup opportunities with Democratic incumbent Doug Jones the most vulnerable senator on the ballot this year. The crowded GOP primary, which also featured Rep. Bradley Byrne and former Auburn football coach Tommy Tuberville, is expected to go to a runoff.

In California, former House Republicans looking for a comeback include David Valadao and Darrell Issa. Valadao is running to regain the 10th District seat he lost in 2018. Darrell Issa is running for the 50th District, which adjoins the district he previously represented. Issa is locked in a heated race with former San Diego City Councilmember Carl DeMaio in the race to replace former GOP Rep. Duncan Hunter, who resigned at the beginning of the year after pleading guilty to misusing campaign funds.

Former GOP Rep. Pete Sessions is also eyeing a return, running for the open seat in Texas’ 17th District, which is more Republican-leaning than the Dallas-area seat he lost in 2018. There’s a familiar face for another deep-red open seat in Texas with former White House physician Ronny Jackson running in 13th District. Both races are expected to go to a runoff.

Elsewhere in Texas, Democrat Wendy Davis, a former state senator who ran unsuccessfully for governor in 2014, is running to take on GOP Rep. Chip Roy in the 21st District. Davis is expected to avoid a runoff since only one other Democrat is running.

3. Second time’s the charm

Several candidates who are making a second run for Congress after losing in 2018 have primaries Tuesday. Some who came close to winning the last time appear poised to advance past their primaries this year, including Republican Young Kim, who nearly defeated Democratic Rep. Gil Cisneros in California’s 39th District, and Democrats Gina Ortiz Jones in Texas’ 23rd and Ammar Campa-Najjar in California’s 50th.

In Texas’ 22nd District, Sri Preston Kulkarni has led the Democrats in fundraising and could avoid a runoff after coming within 5 points of retiring GOP Rep. Pete Olson in 2018. Ortiz Jones, Campa Najjar and Kulkarni are all competing in open seats this year.

Other candidates have faced more competitive primaries despite being their party’s nominee in 2018. Mike Siegel is running again in Texas’ 10th District, but that Democratic primary could go to a runoff. EMILY’s List has backed lawyer Shannon Hutcheson but hasn’t spent in the primary. A group that backs candidates with STEM backgrounds, 314 Action Fund, has spent $364,000 to bolster physician Pritesh Gandhi. The winner will face GOP Rep. Michael McCaul in a race rated Likely Republican.

Jan McDowell, an accountant, might not even make the runoff in Texas’ 24th District, despite coming within 3 points of GOP Rep. Kenny Marchant in 2018. Marchant is retiring, and the open seat is a top Democratic pickup target. In the primary, McDowell has been outraised by former Air Force Col. Kim Olson and former local school board member Candace Valenzuela. EMILY’s List has spent $209,000 to support Valenzuela.

In North Carolina, Kathy Manning had the Democratic Congressional Campaign Committee’s support for her 2018 bid in the 13th District. But she’s now running in a contested primary in the 6th, which became more Democratic after recent redistricting.

North Carolina’s 2nd, which also shifted toward Democrats in redistricting, features another familiar face. Former state Rep. Deborah Ross, who ran unsuccessfully for Senate in 2016, is running there. Both Manning and Ross are competing in primaries that have centered on identity politics.

4. GOP women face first hurdle

More than a quarter of the Republican women running for the House are competing in primaries Tuesday, including several who have earned the backing of GOP women’s groups. Those candidates include Kim, who has cleared her primary field, and fellow Californian Michelle Steel, who is running in the 48th District. Multiple women’s groups have also endorsed Texas Republicans Genevieve Collins, a businesswoman running in the 32nd District, and Beth Van Duyne, a former Irving mayor running in the 24tht. Some GOP women’s groups are also backing Jessica Taylor in Alabama’s 2nd, which Republican Martha Roby is vacating. Both Texas primaries and the Alabama race could head to a runoff given the number of GOP candidates in those races.

VIEW PAC, which supports Republican women, has also endorsed former Bellaire Mayor Cindy Siegel, who faces Army veteran Wesley Hunt in the primary for Texas’ 7th District. It’s unclear if Siegel will force Hunt, who has the backing of top GOP leaders and Trump, into a runoff. VIEW PAC has also endorsed Monica de la Cruz-Hernandez in the more Democratic 15th District in Texas.

Although no GOP women’s groups have taken sides in California’s 45th District primary, it features two Republican women, Peggy Huang and Lisa Sparks, in a crowded race to take on Democratic Rep. Katie Porter.

5. What’s in an endorsement?

Tuesday’s primaries will be another test of the power of Trump’s endorsement in Republican primaries. The president has backed Granger and Hunt, and a handful of other candidates who also have support from House Minority Leader Kevin McCarthy.

In Texas, Trump also endorsed Van Duyne and August Pfluger, a former National Security Council adviser running in the open 11th District, which could head to a runoff since there are nine other Republicans on the ballot. Trump has also endorsed California state Assemblyman Jay Obernolte in the open 8th District.

The president isn’t the only one picking sides. Some outgoing lawmakers have signaled their preferred successors, who first have to win their primaries on Tuesday.

Retiring North Carolina Rep. Mark Meadows recently endorsed activist Lynda Bennett, the only woman in the crowded GOP primary to replace him in the 11th District. A former aide to Meadows is also running. And in Texas’ 23rd District, retiring GOP Rep. Will Hurd has endorsed Navy veteran Tony Gonzales.

6. Senate scramble

Tuesday will also test whether the Democratic Senatorial Campaign Committee gets its preferred candidates in North Carolina and Texas.

In North Carolina, former state senator and Army veteran Cal Cunningham, who has been endorsed by the DSCC, is expected to win the Democratic nod. But Tuesday will show whether Republican meddling in the primary had any impact. Senate Leadership Fund, a super PAC aligned with Senate Majority Leader Mitch McConnell, paid for ads bolstering state Sen. Erica Smith, the more liberal candidate. The ploy forced Cunningham and his allies to spend resources ahead of the primary, but Democrats don’t think that will ultimately hurt Cunningham’s bid to take on GOP Sen. Thom Tillis.

In Texas, the DSCC has endorsed Air Force veteran MJ Hegar, who ran unsuccessfully for the House in 2018. Hegar’s primary has highlighted a divide in the party over winning strategies, and it is expected to go to a runoff.

7. It’s special

A special election is also taking place Tuesday in California’s 25th District, which opened up after Democrat Katie Hill resigned. Hill stepped down after illicit photos of her were released online amid allegations of inappropriate relationships with a campaign staffer, which she admitted to, and a House staffer, which she denied.

Hill flipped the 25th District from red to blue in 2018, and Democrats are looking to hold on to the Southern California seat. Clinton carried the district by 7 points in 2016, and Inside Elections rates the race Likely Democratic.

If a candidate receives a majority of the vote on Tuesday, he or she would win the special election outright. But that is not expected to happen since there are a dozen candidates on the ballot.

If no one wins a majority of the vote, the top two candidates, regardless of party affiliation, would advance to a May 12 runoff. Democratic Assemblywoman Christy Smith is expected to advance to the runoff. On the Republican side, the top two candidates are former GOP Rep. Steve Knight, whom Hill defeated in 2018, and Navy veteran Mike Garcia.

Outside Democratic groups have been spending in the race. There have been some signs that Democrats would rather face Knight in May, since they already have a playbook to defeat him from 2018. The DCCC and House Majority PAC, a super PAC aligned with Pelosi, have together spent more than $969,000 on the primary.

The primary for the full term in the 25th District is also on the ballot Tuesday, which has raised some concerns about voters being confused by having to vote twice in the same congressional district.

Stephanie Akin contributed to this report.