John Cornyn

Republicans and Democrats are picking party nominees in a slate of other races, from attorney general to congressional seats that could help determine partisan control in Washington. If no single candidate won at least 50% of the vote in the March 3 primary, the top two finishers head to a runoff.

Runoffs often are decided by a tiny slice of the electorate, far less than the tally in primaries. That has campaigns racing to turn out a relatively small pool of voters. Here’s what to know about the runoff:

Early voting will last just one week, from Monday through Friday, with no weekend hours.

Senate: Incumbent John Cornyn is seeking to fight off a GOP challenge from outgoing Attorney General Ken Paxton. Cornyn has spent millions on ads targeting the attorney general’s personal conduct, while Paxton has blasted the senator as out-of-touch with the party’s MAGA base.

Attorney general: The race to replace Paxton is hotly contested. State Sen. Mayes Middleton of Galveston took first place in March and is backed by Gov. Greg Abbott and Lt. Gov. Dan Patrick. U.S. Rep. Chip Roy of Austin is endorsed by U.S. Sen. Ted Cruz and many fellow House Republicans.

Railroad commissioner: The chairman of Texas’ oil and gas agency, Jim Wright, is being challenged by Bo French, a conservative who has come under fire from fellow Republicans for incendiary social media posts.

Attorney general: State Sen. Nathan Johnson of Dallas came close to winning the March primary outright but was pushed into a runoff against former Galveston Mayor Joe Jaworski.

U.S. House: In North Texas, U.S. Rep. Julie Johnson is facing a challenge from former U.S. Rep. Colin Allred, who formerly represented the area in Congress but left to pursue a failed bid for the Senate.