As a long and contentious primary season nears its end, attention is turning to Florida, Wyoming, California and Alaska, where primaries Tuesday will highlight Republican-led redistricting efforts that have scrambled congressional maps and new battles between the Democratic establishment and progressive left.

Also in the mix are a handful of scandal-plagued candidates, multiple people running with matching last names and several incumbents at risk of defeat.

Tuesday's contests will help shape the fiercely contested midterms this fall to determine control of Congress, where Republicans have a narrow edge, and offer a referendum on President Donald Trump's second term.

Here's a closer look at what to watch.

Historic slate of Black candidates for governor emerging

Trump-backed Florida Rep. Byron Donalds, a rising star in the Republican Party, is running to succeed term-limited Gov. Ron DeSantis to become the first Black governor of the state. If Donalds wins, he'll become part of a historic slate of Black gubernatorial nominees that includes Republican Rep. John James in Michigan and Lisa Demuth, who defeated pillow-selling conspiracist Mike Lindell in Minnesota.

On the Democratic side, David Crowley won a razor-thin primary against a democratic socialist in Wisconsin, joining Attorney General Aaron Ford in Nevada, State Rep. Jermaine Johnson in South Carolina, and former Atlanta Mayor Keisha Lance Bottoms, who is running in Georgia to be the nation's first Black woman governor.

There is currently only one Black governor in the nation, Democrat Wes Moore of Maryland, who is seeking reelection in November.

The Florida GOP winner will likely face David Jolly, a former Republican-turned-independent-turned-Democrat.

Redistricting creates skirmishing for Democrats in Florida House races

A GOP-led redrawing scrambled Florida's congressional map, which has created some awkward matchups.

The most contentious pits veteran Democratic U.S. Rep. Debbie Wasserman Schultz against former U.S. Rep. Sheila Cherfilus-McCormick in a South Florida district that is almost majority Black. Cherfilus-McCormick resigned earlier this year under threat of House ethics sanctions, but now wants her seat back.

Wasserman Schultz, a former national party chair seeking a 12th term in Congress, is the only white candidate competing against four Black candidates in an area of Broward County that has helped send Black Democrats to Congress since 1992. Her decision to run has raised questions about representation and stirred deep animosity, including charges by one rival that “she stabbed us in the back."

Carpetbaggers and comebacks in the making in Florida?

The race to fill Donalds' House seat features a cast of characters akin to a reality show reunion, including several who have spent time in prison and a handful who have run in other states.

The field includes two former members of Congress who are mounting comeback bids after departing in scandal. Former North Carolina Rep. Madison Cawthorn'stenure was marred by repeat traffic stops, guns at airport checkpoints and a claim he had been invited to a Washington orgy. Former New York Rep. Chris Collins, who resigned before pleading guilty to insider trading charges, served prison time before he was pardoned by Trump.

Trump-endorsed Catalina Lauf ran twice for Congress in Illinois. She lost the 2020 primary to Jim Oberweis, a former state senator, who has also decamped to Florida and is running for the seat.

Another candidate, Ola Hawatmeh, previously ran unsuccessfully for Congress in New York, while Linda Sawyer once tried in Michigan.

Also in the race: John Strand, a former television actor, underwear model and romance novel cover model, who served prison time for his role in the Jan. 6, 2021 assault of the U.S. Capitol.

Progressive vs. establishment candidates at odds again

The internal battle between progressive and establishment candidates that has been roiling the Democratic Party in states like Wisconsin, Minnesota and Michigan, now arrives in more conservative territory.

Progressive state lawmaker Angie Nixon is facing retired Army Lt. Col. Alex Vindman, a former National Security Council official who delivered searing testimony against Trump in his 2019 impeachment trial. They're both running in the Florida special election to fill the last two years of Secretary of State Marco Rubio's former Senate term.

The winner is likely to face interim Sen. Ashley Moody, the Republican appointed by DeSantis to the seat.

Other races will also put fault lines on display. In South Florida, U.S. Rep. Jared Moskowitz is running for reelection in a new Republican-friendly district against union organizer and democratic socialist Oliver Larkin.

Meanwhile, Republican incumbents are facing their own challenges. Rep. Cory Mills, running for a third term, has been plagued by an ethics investigation stemming from allegations of assault, domestic violence and campaign finance violations, which he denies.

Double-checking the name in Alaska

In a Senate race that is expected to be one of the country's most closely watched this fall, incumbent Republican Sen. Dan Sullivan, a Trump ally seeking a third term, is facing another candidate also named Dan Sullivan.

Republicans have argued the second Sullivan, who’ll be appearing on the ballot as “Daniel J. Sullivan Jr.," is a sham candidate running at the behest of Democrats to cause confusion. Dan J. Sullivan Jr., a retired teacher, has denied the charge.

Also in the race is former U.S. Rep. Mary Peltola. She was the first Alaska Native to serve in Congress, and she would become the first Alaska Native senator if she wins in November.

Under Alaska’s open primary system, all candidates appear on the same ballot, and the four who receive the most votes move on to a ranked-vote general election.

There are other surnames for Alaskans to keep straight.

Republican Rep. Nick Begich faces a crowded field in his bid for a second term in the state’s lone congressional seat. His uncle, former state Sen. Tom Begich, and former state Rep. Jonathan Kreiss-Tomkins are the two Democrats in the race. Tom Begich is the brother of Mark Begich, a former Democratic U.S. senator whom Sullivan defeated in 2014.

Seats open up in Wyoming

For the first time in more than 30 years, Wyoming has open seats for governor, U.S. Senate and U.S. House all up for grabs in a state where registered Republicans outnumber Democrats by a 7-to-1 margin.

Republican Sen. Cynthia Lummis' decision to retire after a single term has set off a chain reaction, with Rep. Harriet Hageman running to replace her.

She has an overwhelming fundraising advantage and became well-known after defeating former Rep. Liz Cheney, one of Trump's harshest Republican critics, in 2022.

Nine Republicans, meanwhile, are competing to replace Hageman as the state's lone U.S. representative.

Wyoming’s current governor, Republican Mark Gordon, considered seeking a third term and challenging a state term limit law but ultimately decided not to.

Pro-Israel group spending in former Swalwell seat

In California's Bay Area, voters will be picking a replacement for Democratic Rep. Eric Swalwell, whose resignation amid sexual assault allegations ended his run for governor.

California's 14th District will remain under Democratic control as state Sen. Aisha Wahab and Bay Area Rapid Transit Board President Melissa Hernandez advanced from a special open primary.

The race is reprising a theme that cropped up in other Democratic primaries this year: outside spending, particularly from pro-Israel lobbying groups. The American Israel Public Affairs Committee's super PAC has spent more than $2 million against Wahab and backing Hernandez, and another group with funding from the super PAC has spent nearly $2 million in support of Hernandez.

Pro-Israel group spending seemed to backfire in Michigan's recent Democratic Senate primary, where Abdul El-Sayed emerged victorious despite tens of millions of dollars backing his opponent Rep. Haley Stevens.