The increasingly acrimonious split between former Vice President Mike Pence and former President Donald Trump widened Monday as Pence endorsed another GOP gubernatorial primary candidate running against Trump’s preferred choice.

You don’t have to care much about Arizona politics to get the import of yet another sign of the slow-motion divorce between Trump, who continues to relitigate the 2020 election results, and other Republicans looking more to the future of the Republican Party – and themselves.

Pence endorsed Karrin Taylor Robson, a member of a longtime Arizona Republican family and the state Board of Regents. She’s also been endorsed by term-limited Gov. Doug Ducey, former governors Jan Brewer and Fyfe Symington, and former Rep. Matt Salmon.

Trump has endorsed a former local TV anchor Kari Lake, who has enthusiastically supported Trump’s claim that the 2020 presidential election was stolen and fraudulent.

Both Pence and Trump will campaign in Arizona on Friday for the Aug. 2 primary race that has now exceeded $15 million in spending.

Unlike other Republicans who’ve shied away from direct confrontation with the 45^th president and his slightly diminished but fervent band of loyal supporters, Pence has apparently decided that his best path to the party’s 2024 presidential nomination is not around Trump, but through him.

It’s a high-stakes risk for a high-stakes task for the former VP. Pence, who just turned 63, is counting on his staunchly conservative record in the House, as Indiana governor, and as vice president combined with his character, and close association with Trump’s economic, energy, and foreign affairs successes.

He hopes that will appeal to voters turned off by the Trump tumult, his behavior, outbursts, and rigid refusal to accept the 2020 election results, that is, GOP and independent voters who didn’t vote or drifted off to support Biden as a lame alternative.

It’s an unexpected turn. For four years Pence was the closest political partner and most loyal and vocal advocate for Trump, who would be 78 in 2024, the same age as Biden when elected as the oldest president ever.

But then Trump turned against the vice president for not opposing the election’s certification on Capitol Hill in January, 2021.

This is the second time Pence has campaigned against Trump’s gubernatorial primary choice. In Georgia, Pence endorsed incumbent Gov. Brian Kemp over former Sen. David Perdue, who was recruited by Trump to challenge Kemp for not overthrowing the state’s 2020 election results.

“When you say yes to Gov. Brian Kemp tomorrow,” Pence said then, “you will send a deafening message all across America that the Republican Party is the party of the future.”

Kemp went on to destroy Perdue by 52 points in the May 24 primary, which damaged the former president’s record of successful endorsements.

His numerous endorsements of Republican candidates in the Nov. 8 midterms are a gamble for the former casino operator as results will be closely watched to measure Trump’s ongoing influence within the party of Lincoln as attention turns to the 2024 presidential cycle.

A poor or mixed showing will tempt other GOP officeholders to join in primary bids, if only to raise their national profile for later cycles and build donor networks.

It is widely assumed that Trump will seek to become only the second president to lose reelection, then return to the White House four years later. Grover Cleveland was elected in 1884 and 1892, one of only two Democrats to occupy the White House (Woodrow Wilson) during a 72-year reign of Republicans from 1860 to 1932. That marathon run of successes began with Abraham Lincoln, the party’s first president, and ran through Herbert Hoover, the last cabinet member to become president.

We analyzed Trump’s decision and outlook in our Sunday column here.

Modern vice presidents have encountered mixed success inheriting or capturing the presidency. George H.W. Bush, Richard Nixon, and Joe Biden ultimately did. But Al Gore, Walter Mondale, and Hubert Humphrey failed.

Lyndon Johnson, who inherited the White House with John Kennedy’s assassination, won his own election in 1964 but abandoned reelection in 1968 in the face of Vietnam War opposition.

Arizona, home to the GOP’s nominees in 1964, Barry Goldwater, and 2008, John McCain, was once a solid GOP state. But with 2020 voter turnout just a hair under 80 percent, Trump lost Arizona’s 11 electoral votes to Joe Biden by 10,457 votes out of more than 3.3 million cast.

Trump has also denounced Arizona’s Ducey for not overthrowing the narrow presidential election results in his state.

Pence called Robson “the best choice for Arizona’s future.” Pence added:

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.

She replied:

Modern politics is full of charlatans and fakes, but Vice President Pence is the genuine article. He has never wavered in his conservative beliefs and commitment to our Constitution, and left a rock-solid legacy as (Indiana) Governor to which I will aspire.

Lake has taken aggressive stances on a number of issues. She’s suggested declaring an invasion on the southern border to address the illegal immigrant influx. She wants to finish the wall started by Trump and said bombing could be used on the underground tunnels used by Mexican drug cartels.

“I don’t care what Joe Biden says,” Lake told the Arizona Republic. “He’s an illegitimate president, and if he wants to try to stop us, then he can come down here and try to stop us.”

In April, an Arizona poll showed Lake, a former supporter of Barack Obama, running away with the governor’s race with a 30 to 9.5 percent lead over Robson. However, a newer poll earlier this month found a statistical dead heat with both women in the high 30 percent area.