By Tim Reid
(Reuters) -Former Vice President Mike Pence, who served Donald Trump with unwavering loyalty but later turned on him after the 2021 attack on the U.S. Capitol, formally challenged his former boss for the Republican presidential nomination on Wednesday.
Pence joined a crowded field of Republican White House hopefuls challenging Trump for the party's presidential nomination. Former New Jersey Governor Chris Christie entered the race on Tuesday, while North Dakota Governor Doug Burgum jumped in on Wednesday, raising the number of candidates into double digits.
"I'll always be proud of the progress we made together for a stronger and more prosperous America," Pence said in his campaign video, criticizing current Democratic President Joe Biden but never citing Trump by name.
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 U.S. history. Pence enters the Republican presidential primary with a mountain to climb, polling at just 5% and trailing Trump by 44 points, according to a Reuters/Ipsos opinion poll in May.
Pence, who turns 64 on Wednesday, joins a nominating contest that is currently a two-man race between Trump and Florida Governor Ron DeSantis.
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 will hold a campaign kick-off event later on Wednesday near Iowa's capital Des Moines, followed by a CNN town hall event Wednesday evening.
Pence, a conservative Christian, will focus much of his campaigning on Iowa, the first state to vote in the nominating contest next year. Iowa 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.
During Trump's tumultuous four years in the White House, Pence repeatedly defended him through multiple scandals.
But Pence 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 over Trump in the 2020 election.
Pence said he had no constitutional authority to meddle with the election results. Trump supporters stormed the Capitol during the certification process on Jan. 6, 2021, forcing Pence, lawmakers and staff to flee to safety.
"I had no right to overturn the election, and his reckless words endangered my family and everyone at the Capitol that day, and I know that history will hold Donald Trump accountable," Pence said in March.
In Twitter posts during the certification, Trump accused Pence of cowardice. Some rioters chanted for Pence to be hanged.
Trump, in remarks to conservative commentator Todd Starnes on Monday, wished Pence luck, but criticized 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."
Many of Trump's diehard supporters view Pence's refusal to overturn the election result as treachery, and would seek to block his path to the nomination.
Pence, who served as governor of Indiana and is a former congressman, still embraces many of Trump's policies while portraying himself as an even-keeled and consensus-oriented alternative.
The success of his campaign will hinge on whether he can attract enough backers of Trump's policies who are turned off by the former president's rhetoric and behavior to build a viable coalition.
In his video Pence said the American dream was being "crushed under runaway inflation" as wages fell, recession loomed, and risks from unchecked immigration grew. He also said, over images of the leaders of Russia and China, that "the enemies of freedom are on the march around the world".
"Worse still, timeless American values are under assault as never before," he added, over video of news reports featuring police tape, transgender athletes, and drag queens.
He did not mention abortion but did say his candidacy could "give America a new beginning for life".
Christie on Tuesday launched his campaign with a withering attack on Trump, calling him a "self-serving mirror hog" and faulting other rivals for avoiding direct confrontation with the former president.
Christie, 60, was an adviser to Trump's 2016 White House campaign but has since become a vocal critic over Trump's false claims that the 2020 election was rigged.
Burgum, 66, a wealthy former software executive who is largely unknown beyond his state, said he was a boy from rural North Dakota who rose from being a chimney sweep to found a billion-dollar IT company, before becoming a governor who cut red tape and taxes.
"To unlock the best of America, we need a leader who's clearly focused on three things: economy, energy and national security," Burgum said in his announcement speech.
(Reporting by Tim Reid; Additional reporting by Susan Heavey; Editing by Ross Colvin, Grant McCool, Angus MacSwan and Daniel Wallis)
