10 races to watch Tuesday, led by Senate contests in Pennsylvania and North Carolina

May's busy primary calendar continues Tuesday, with five states holding elections.

Primaries for open U.S. Senate seats in Pennsylvania and North Carolina headline Tuesday's races. Both battleground states present Democrats with opportunities to pick up a Senate seat as they try to maintain narrow control of the chamber.

Idaho, Oregon and Kentucky also have notable contests. Here are 10 races to watch:

1. Pennsylvania Senate

Thanks to the retirement of Republican Pat Toomey, Pennsylvania has an open Senate seat for the first time in a dozen years. And this race has had more than its share of plot twists — including two Donald Trump endorsements over the past nine months.

On the Republican side, after Trump's first preferred choice dropped out amid domestic abuse allegations, two new, high-profile candidates entered the primary: Celebrity doctor Mehmet Oz and former hedge fund CEO David McCormick, who had served in the George W. Bush administration and who's married to a former top adviser to Trump.

McCormick and Oz worked hard to win Trump's endorsement. Oz won out, giving his campaign a boost, but that didn't stop McCormick from running ads featuring Trump praising the candidate. For months, polling has had the two jockeying for the top spot in the race, with Oz holding a very small lead since getting the nod from Trump.

But now, in the final weeks of the race, another candidate has surged into the top tier. Kathy Barnette — a Black GOP activist and author best known for her appearances as a commentator on Fox News — has done it by proclaiming to be more MAGA than even Trump, and despite having just a fraction of the money to spend that the very wealthy McCormick and Oz have. Her rise has surprised political analysts, who suggest she may be benefitting from conservative discontent with Trump's choice of Dr. Oz.

For Democrats, the primary features a matchup between Lt. Gov. John Fetterman, a former small-town mayor who backed Bernie Sanders' 2020 presidential run, and Rep. Conor Lamb. The 6-foot-9 Fetterman has the persona of an authentic anti-politician, while Lamb has a reputation as a moderate who can win votes in places where Democrats have struggled in recent elections.

Also in the race is state Rep. Malcolm Kenyatta, who is looking to become the first ever LGBTQ candidate elected to statewide office in Pennsylvania.

Despite expectations of a close contest, polls have consistently given Fetterman a lead of more than 20 points, with Lamb a distant second and Kenyatta even further back. (Fetterman suffered a stroke in recent days but said it wouldn't derail his campaign.)

2. North Carolina Senate

This Senate seat is open thanks to another GOP retirement: Sen. Richard Burr, who announced in 2016 he would not seek another term. Trump's daughter-in-law Lara Trump briefly considered a Senate run in her native state, but decided not to pursue it. Nevertheless, the former president weighed in early, backing Rep. Ted Budd last June.

Helped by outside money, Budd has emerged ahead of Pat McCrory, a former North Carolina governor who gained national prominence when he signed the state's "bathroom bill" which targeted trans people and required people to choose bathrooms based on the sex listed on their birth certificate.

Whoever wins on the GOP side will likely face Cheri Beasley, who was the first Black woman to serve as chief justice of the North Carolina Supreme Court.

3. Pennsylvania Governor

Just days before the primary, Trump endorsed Pennsylvania state Sen. Doug Mastriano to be governor. Mastriano has peddled Trump's election lies, and was present near the U.S. Capitol on Jan. 6, 2021. (He says he left as the event became violent.) Republicans have been fractured, with many concerned that Mastriano can't win statewide in November. Some other candidates in what started as a crowded field dropped out and have endorsed former Rep. Lou Barletta, but Mastriano's lead in polls and Trump's endorsement place him as the likely winner Tuesday night.

Meanwhile, the presumptive Democratic nominee is state Attorney General Josh Shapiro, who is already running against Mastriano's extremist messaging.

4. Idaho Governor

In Idaho, Republican Gov. Brad Little is facing a challenge from his Trump-backed lieutenant governor, Janice McGeachin. McGeachin is a former state legislator who battled with Little over COVID-19 restrictions.

Polling and fundraising show Little in the lead, but the primary puts McGeachin's ties to the far right on display in one of the most conservative states in the country.

5. North Carolina's 11th Congressional District

GOP Rep. Madison Cawthorn faces a crowded field of primary challengers in a district that's likely going to remain red in November. Cawthorn, who has Trump's support, has been involved in several scandals that have raised skepticism as to whether he can keep his seat.

In North Carolina, a winner needs to cross a 30% threshold to avoid a runoff.

6. North Carolina's 4th Congressional District

There are a several notable primaries Tuesday that show divides within the Democratic Party.

In North Carolina, the 4th District, which encompasses the blue cities Durham and Chapel Hill, is open after longtime Rep. David Price announced his retirement.

And it's become an expensive contest, with candidates like state Sen. Valerie Foushee, who is more moderate, and Durham County Commissioner Nida Allam, who has received endorsements from Vermont Sen. Sanders and New York Rep. Alexandria Ocasio-Cortez.

Abortion has risen as an issue after the leak of a draft Supreme Court opinion on Roe v. Wade. Allam, who's 28, has been open about her own abortion story.

Former American Idol star Clay Aiken is also in the race.

7. Oregon's 6th Congressional District

Nine Democratic candidates are in the primary race for a new district in Oregon that has become the third most-expensive House Democratic primary in the country. Candidate Carrick Flynn has been drawing questions for funding he's getting from a political action committee backed by a cryptocurrency billionaire.

8. Kentucky's 3rd Congressional District

Democratic Rep. John Yarmuth, who chairs the powerful House Budget Committee, is retiring from his seat, leaving seven Republican candidates and two Democrats trying to replace him. The district is expected to remain safely blue.

9. Oregon's 5th Congressional District

Democratic Rep. Kurt Schrader is facing a progressive challenge from Jamie McLeod-Skinner, in a district that was recently redrawn and is considered a potential pickup opportunity for Republicans. Schrader is backed by President Biden.

10. Pennsylvania's 7th Congressional District

It could also be a tight race in November between whoever wins the Republican primary Tuesday night and incumbent Democratic Rep. Susan Wild. Former Lehigh County Commissioner Lisa Scheller, who nearly won in 2020 against Wild, appears to be in the lead but faces opposition from business owner Kevin Dellicker.

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