The midterm elections officially begin Tuesday with primaries in Texas, North Carolina and Arkansas. As war with Iran breaks out, Democrats and Republicans are figuring out who they want to lead their party into November’s general election, when control of Congress and statehouses around the country will be up for grabs.

The most hotly contested races of the day are in Texas, with fierce competition on both sides of the aisle for U.S. Senate nominations. It’s possible that the Republican campaign will continue into a runoff.

Here’s the latest:

Sarah Sanders, Tom Cotton among Republicans on Arkansas ballot

Republican incumbents, including U.S. Sen. Tom Cotton, are heavy favorites to win their primaries in Arkansas.

Cotton, who is seeking his third term in office, will face Jeb Little, an Arkansas State Police trooper, and Micah Ashby, a minister from Bradford.

Republican Gov. Sarah Huckabee Sanders, who served as President Donald Trump’s press secretary during Trump’s first term, is seeking her second term in office. She did not draw a Republican opponent.

Arkansas hasn’t elected a Democrat statewide since 2010, and Sanders and Cotton will be heavy favorites to win reelection in November.

All polls in Texas are now open

Polls have now opened for voters in El Paso and Hudspeth counties, an area of about 1 million people on the western tip of Texas in the Mountain Time Zone.

Voting is underway in Arkansas

Polls in Arkansas are open from 7:30 a.m. to 7:30 p.m., and voters are required to show photo identification before voting.

Primary election day starts in North Carolina, with US Senate nominations at stake

About 2,600 sites nationwide opened at 6:30 a.m. ET and will close at 7:30 p.m. ET. Some ballots have already been cast by mail or during an early in-person voting period that ended Saturday.

There’s an open race for a seat in the U.S. Senate because Republican Sen. Thom Tillis decided not to seek reelection after clashing with Trump. Former Gov. Roy Cooper is seeking the Democratic nomination, while former Republican National Committee Chairman Michael Whatley is running to represent his party.

Voters are also picking nominees for U.S. House seats, including the Republican choice to challenge Democratic Rep. Don Davis in the 1st District. That district became more Republican as state legislators redrew it during Trump’s redistricting effort to help his party maintain control of the House.

The Associated Press