(CBS) — Gov. Bruce Rauner, a Republican, will not attend his national party’s nominating convention later this year, when controversial GOP presidential candidate Donald Trump is expected to be nominated, nor will he endorse Trump.

Sources in the governor’s office Thursday confirmed a report in the Chicago Tribune that Rauner will pass on attending the Republican National Committee event in Cleveland, scheduled for July, and will decline to back Trump. One source tells CBS 2 Rauner has a “distaste for the rhetoric” for which the Trump campaign has become known.

Bruce Rauner speaking to reporters

Gov. Bruce Rauner (CBS)

Trump, the brash billionaire real-estate developer and former television personality, became the presumptive GOP nominee for president this week when the last of his primary opponents suspended their own campaigns. Some in the party establishment consider it a disaster, given Trump’s bruising rhetoric.

Other notable Republicans staying away from Cleveland include former President George W. Bush and U.S. Sen. Mark Kirk, an Illinois Republican who is running for re-election in a state that has typically leaned Democratic.