Pence issued his most forceful condemnation to date of Trump's role in the attack of January 6, 2021, when the then-president's supporters stormed the US Congress to try to stop lawmakers from certifying Democrat Joe Biden's election victory.
"I believe that anyone who puts themselves over the Constitution should never be president of the United States, and anyone who asked someone else to put them over the Constitution should never be president of the United States again," Pence said in a speech in Iowa on Wednesday, which kicks off the Republican nominating contest next year.
It was an extraordinary attack by Pence, not only because he has mostly shied away from attacking Trump (76) directly until now, but also because the January 6 attack is rarely mentioned by other Republican presidential hopefuls.
They view it as politically toxic, fearful that condemning the attack and Trump's part in it will alienate Trump's supporters and other Republican primary voters.
Trump is currently the front-runner in the Republican race.
Pence is placing a high-risk bet that voters in the nominating contest will reward him for backing the Constitution, rather than Trump.
Pence said Trump's actions on that day "endangered my family and everyone at the Capitol."
During Trump's tumultuous four years in the White House, Pence repeatedly defended him through multiple scandals. But he incurred the wrath of Trump and his supporters when, as ceremonial president of the Senate, he refused to stop the certification of Biden's victory.
Pence, who turned 64 on Wednesday, joins a crowded nominating contest that is currently a two-man race between front-runner Trump and Florida Governor Ron DeSantis. Former New Jersey Governor Chris Christie and North Dakota Governor Doug Burgum also announced candidacies this week, raising the number of Republican White House hopefuls into double digits.
It is extremely rare for a vice president to run against a president he served under, and it has happened just a handful of times in US history. Pence enters the Republican primary with a mountain to climb, polling at just 5% and trailing Trump by 44 percentage points, according to a Reuters/Ipsos opinion poll in May.
Pence said on Wednesday he had no constitutional authority to meddle with the election results and that Trump had been "wrong." In Twitter posts on January 6, Trump accused Pence of cowardice.
Trump supporters stormed the Capitol during the certification process, forcing Pence, family members, lawmakers and staff to flee to safety. Some rioters chanted for Pence to be hanged.
"The American people deserve to know that on that day, President Trump also demanded that I choose between him and the Constitution. Now voters will be faced with the same choice. I chose the Constitution and I always will," he said.
Pence will follow his announcement with a CNN town hall event Wednesday evening.
The growing number of candidates could clear the way for a Trump victory, because they risk splintering the anti-Trump vote, letting the former president clinch the nomination like he did in similar circumstances in 2016, party members and strategists said.
Pence, a conservative Christian, will focus much of his campaigning on Iowa. The state has a significant number of evangelical voters among its Republican electorate. Pence hopes a strong showing in the state will give him momentum and propel him into contention.
ABORTION, UKRAINE
In his Iowa speech, Pence accused Trump of treating abortion as "an inconvenience." As president, Trump appointed conservative US Supreme Court justices who helped end the national right to abortion last year.
"Donald Trump and others in this race are retreating from the cause of the unborn," Pence said.
Trump has declined to back a federal law restricting abortion rights, saying the issue should be left to individual states. Pence backs Congress passing a law enshrining abortion restrictions nationally.
Pence also took a swipe at DeSantis, a leading contender for the nomination, for saying that Russia's invasion of Ukraine was a "territorial dispute," a remark DeSantis later walked back.
"I know the difference between a territorial dispute and a war of aggression," Pence said.
Trump, in remarks to conservative commentator Todd Starnes on Monday, wished Pence luck, but criticised him for allowing the certification of the 2020 election results.
"We had a strong, nice relationship until the very end," Trump said. "We disagreed on that last moment in time on that very issue."
