Pence breaks with Trump again in endorsement for Arizona governor.

Former Vice President Mike Pence endorsed Karrin Taylor Robson instead of Kari Lake in Arizona’s Republican primary for governor on Aug. 2, pitting him against former President Donald J. Trump in another closely watched race.

Mr. Pence’s endorsement, announced by Ms. Taylor Robson’s campaign, came amid pushback from some Republicans against Mr. Trump and the candidates he has endorsed who echo his false claims of widespread election fraud in 2020 — as Ms. Lake has done.

Gov. Doug Ducey, who has reached his term limit, has also backed Ms. Taylor Robson, as have other prominent Republicans like Chris Christie of New Jersey.

“As Arizona Democrats pursue the reckless Biden-Harris agenda, Karrin Taylor Robson is the only candidate for governor that will keep Arizona’s border secure and streets safe, empower parents and create great schools, and promote conservative values,” Mr. Pence said in a statement. “Karrin is the best choice for Arizona’s future, and I am proud to support her.”

Public polling has indicated that Ms. Taylor Robson is closing the gap with Ms. Lake, who was once a supporter of former President Barack Obama, and that the race is now competitive.

Mr. Trump and Mr. Pence are set to appear at separate upcoming campaign events in Arizona. Mr. Trump rescheduled a rally for this Friday that was originally set for last weekend after his first wife, Ivana Trump, died unexpectedly.

The two have split on endorsements before: In May, Mr. Pence backed Gov. Brian Kemp of Georgia, who was once Mr. Trump’s top target for retribution because Mr. Kemp refused to call a special session of the legislature after the 2020 election. Mr. Trump endorsed the former Senator David Perdue.

Mr. Kemp won by a wide margin.

Mr. Pence’s life was endangered when supporters of Mr. Trump stormed the U.S. Capitol during the certification of Joseph R. Biden Jr.’s presidential win on Jan. 6, 2021. Mr. Pence has said that Mr. Trump’s assertions that he had the ability to block the certification and determine the election’s outcome are “wrong.”

Arizona was a focal point of Mr. Trump’s efforts to undermine the outcome of the election. Fox News and The Associated Press said early that Mr. Biden had won the state, sparking fury from Mr. Trump and frantic efforts to undo the call.