Cornyn Runoff Showcases Republican Seniority at Risk in Midterms

For Republicans, more than John Cornyn’s 23-year Senate career is on the line in next week’s Texas GOP primary runoff, after President Donald Trump’s last-minute endorsement of state Attorney General Ken Paxton.

The party’s institutional knowledge in the Senate could face a reset next year, even if the GOP retains control of the chamber in November’s midterms.

Sen. Bill Cassidy (R-La.), who chairs a key health committee, lost his primary over the weekend. Sen. Susan Collins (R-Maine), the Appropriations chair, is a top Democratic target this fall. Sen. Mitch McConnell (R-Ky.), the party’s former leader, is retiring. And even Sen. ...