Primary elections on Tuesday in fives states see crowded fields of both Republicans and Democrats hoping to make the ballot in 2020.

What to watch: Rep. Rashida Tlaib (D-Mich.) is "fighting for her political life" in a tight primary race against Detroit City Council President Brenda Jones, who Tlaib beat by 900 votes in 2018, The New York Times writes. Senate Republicans are also watching the primary race in Kansas to see who could replace retiring Republican Sen. Pat Roberts.

Races to watch

In Michigan, both the Democratic and GOP primaries are worth watching as Tlaib finds herself in a rematch against Jones and Rep. Justin Amash's retirement leaves his seat up for grabs.

• Tlaib, one of the first Muslim women elected to Congress, has built a national profile as a part of "The Squad."
• She has also drawn attention for being vocal against President Trump and called for his impeachment. However, her critics say it takes away from her ability to serve her district — one of the poorest in the U.S.
• Five Republicans are vying for Amash's seat while former Democratic Department of Justice attorney Hillary Scholten is running unopposed.
• Amash's district typically leans right, but Democrats have their eyes on the suburban area and hope to claim it in November, per NPR.

In Kansas, nearly a dozen Republicans are competing to take longtime Sen. Pat Roberts' spot in November's general election. Kansas hasn't seen a Democratic senator since 1932, NPR reports.

• Roberts' retirement comes at a sensitive time for the GOP, as the party hopes to keep his seat red.
• Out of several candidates, the most notable are Rep. Roger Marshall, former Kansas Secretary of State Kris Kobach and businessman Bob Hamilton.
• Worth noting: Republicans worry that if Kobach, a polarizing conservative, wins Tuesday's primary, it could put the GOP's hold on the Kansas seat in jeopardy come November, NBC notes.

In Missouri, Democratic incumbent Rep. William Lacy Clay, who has been in office for nearly 20 years, will face off against progressive nurse and activist Cori Bush.

• This rematch comes after Clay beat Bush in 2018. However, Bush's profile has since risen, after she was featured in the Netflix documentary "Knock the House Down," NPR writes.
• Bush has been endorsed by Sen. Bernie Sanders (I-Vt.) and Rep. Alexandria Ocasio-Cortez (D-N.Y.).

In Arizona, a primary in a Republican-leaning district has become competitive after the House passed an ethics resolution against Republican incumbent Rep. David Schweikert for violating congressional and campaign finance rules, per the Tucson Sentinel.

• Four Democrats are competing for the chance to face off against Schweikert: Karl Gentles, Anita Malik, Stephanie Rimmer and Hiral Tipirneni.
• Malik previously lost to Schweikert in 2018.

In Washington state,Democratic Rep. Denny Heck's retirement incited a 19-candidate primary race, according to The Seattle Times.

• Washington's third congressional district could see another rematch between Republican Rep. Jamie Herrera Butler and political science professor Carolyn Long. The two went head to head in 2018, with Butler winning by a 53-47 margin, however, Long appears to be the favorite this time around, Vox reports.
• Democrat Kim Schrier is fighting to keep her seat in Washington's eighth district after winning in 2018 with seven Republican candidates looking to take the seat from her.
• Schrier is well-funded with $3.2 million in the bank — giving her an edge over any Republican candidate in the race, Vox notes.