Ohio Gov. John Kasich was endorsed by former speaker John Boehner Saturday, just days before the Ohio primary.

"He's my friend," Boehner said of Kasich, according to a Cincinnati.com report.

Boehner's endorsement of his fellow Ohio Republican comes at a critical time. If Kasich loses him state, he will drop out of the race, according to previous statements from Kasich and his campaign. Most polling has Kasich and Trump in a dead heat.

Boehner and Kasich's relationship extends back as early as the 1990s, when they were both in the U.S. House and members of Speaker Newt Gingrich's "Republican Revolution."