Former Vice President Mike Pence greets supporters on June 7, 2023, in Ankeny, Iowa, where he formally announced his candidacy for president.

Watch CNN’s town hall with former Vice President Mike Pence at 9 p.m. ET.

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Former Vice President Mike Pence announced Wednesday he’s running for the 2024 Republican presidential nomination as he delivered his toughest takedown to date of primary rival and former boss Donald Trump, who he said “should never” be president again for his actions in the aftermath of the 2020 election.

At his formal campaign kickoff in Ankeny, Iowa, Pence recalled how Trump had asked him to block the certification of Joe Biden’s 2020 election win as Pence presided over Congress on January 6, 2021.

“The American people deserve to know, on that day, President Trump also demanded I choose between him and the Constitution. Now voters will be faced with the same choice. I chose the Constitution, and I always will,” Pence said to applause from the crowd at Des Moines Area Community College.

“I believe that anyone who puts themselves over the Constitution should never be president of the United States. And anyone who asks someone else to put them over the Constitution should never be president of the United States again,” the former vice president said of his onetime boss, currently the front-runner for the 2024 GOP nomination.

At a CNN town hall later in the day in Des Moines, Pence repeated his criticism of his former boss, but on the subject of Trump’s alleged mishandling of classified documents, he said it would “be terribly divisive to the country” if the former president were to be indicted by federal investigators over his actions and a possible obstruction of justice.

“This kind of action by the Department of Justice I think would only fuel further division in the country,” Pence told CNN’s Dana Bash, before adding later, “I hope the DOJ thinks better of it and resolves these issues without an indictment.”

CNN reported Wednesday that the DOJ recently informed Trump’s legal team that the former president is a target in the special counsel investigation into his possible mishandling of classified documents, according to sources familiar with the matter, a sign that prosecutors may be moving closer to indicting him.

A growing field

Pence – who’s been polling in the single digits – joins a growing field of Republican hopefuls, which so far has been dominated by Trump and Florida Gov. Ron DeSantis. Former South Carolina Gov. Nikki Haley, who served as ambassador to the United Nations, is the other former member of the Trump administration running against the former president. Former New Jersey Gov. Chris Christie, a onetime Trump ally who helped him prepare for the 2020 presidential debates, announced his candidacy Tuesday with a sharp anti-Trump message.

Pence’s team views the early-voting state of Iowa as vital to his chances of securing the nomination.

In his remarks in Ankeny that ran a little over half an hour Wednesday, Pence, who had been a loyal second-in-command to Trump prior to January 6, maintained that he was “incredibly proud” of the Trump-Pence administration’s “accomplishments,” before explaining why he was challenging his onetime ticket mate.

“The former president continues to insist that I had the right to overturn the election. President Trump was wrong then, and he is wrong now. I will always believe, by God’s grace, I did my duty on that day, I kept my oath, to ensure the peaceful transfer of power under the Constitution and the laws of this country,” he said.

Pence speaks in Ankeny, Iowa, on June 7, 2023.

“I stand before you today as a candidate for president to say to the Republican Party, the Republican Party must be the party of the Constitution of the United States,” he said.

A Reagan Republican

Pence, who filed his candidacy with the Federal Election Commission on Monday, released a launch video earlier Wednesday, in which he cast himself as a Reagan Republican seeking to return America to conservative principles.

In the video – which makes no mention of Trump and features no images of the former president – Pence argues that “different times call for different leadership” and that the nation needs a leader “that will appeal, as Lincoln said, to the better angels of our nature.”

“We can bring this country back. We can defend our nation and secure our border. We could revive our economy, and put our nation back on a path to a balanced budget, defend our liberties and give America a new beginning for life,” the former vice president says.

An evangelical Christian, Pence was picked to be Trump’s running mate in the 2016 election in hopes of bolstering his standing among Christian conservatives. While “vice president” is his most known title, Pence is seeking to reintroduce himself to voters as a conservative who served as an Indiana governor and congressman before hitching his career to Trump.

In speeches, Pence has argued for fiscal responsibility, including calling for reforms to entitlement programs, a renewal of American energy, support for Ukraine against Russia’s unprovoked invasion, restrictions on abortion and a return to social conservative principles.

He hit several of those themes in his remarks in Ankeny on Wednesday.

Pence accused Trump and other Republican candidates of “retreating” from their abortion stances.

“The sanctity of life has been our party’s calling for half a century – long before Donald Trump was ever a part of it. Now he treats it as an inconvenience, even blaming election losses on overturning Roe v. Wade,” he said.

Trump earlier this year had argued that it “wasn’t my fault” that Republicans “didn’t live up to expectations” in the 2022 midterms, saying that the “abortion issue” had been poorly handled by many GOP lawmakers, especially those who insisted that the procedure should be barred with no exceptions in the case or rape, incest or life of the mother, which he said “lost large numbers of voters.”

On Wednesday, Pence also slammed Trump for referring to Russian President Vladimir Putin as a “genius” for his invasion of Ukraine, and – without mentioning DeSantis by name – he criticized the Florida governor for suggesting that the war was a “territorial dispute.”

“We must resist the politics of personality and the siren song of populism,” Pence said. “We must stand firm on a traditional Republican agenda of a strong national defense, fiscal responsibility and traditional values that lead us to victory in the past and will lead us to victory again.”

Pence vowed to set the nation back “on a path to a balanced budget” and ramp up domestic American energy. He also promised that he would appoint federal judges who will uphold the Second Amendment and “stand for the sanctity of human life.”

Pence is seen in Ankeny, Iowa, on June 7, 2023.

A path to victory

Following his campaign announcement, Pence told Fox News he would “absolutely support” the GOP presidential nominee when asked if he’d commit to the Republican National Committee’s debate requirement for candidates to sign a pledge “agreeing to support the eventual party nominee.”

“I will absolutely support the Republican nominee for president in 2024, especially if it’s me,” Pence said.

Pence repeated that pledge at the CNN town hall later Wednesday. Pressed on how he could make that commitment while also saying that Trump should not be president, Pence replied, “Because I don’t think Donald Trump is going to be the nominee.”

Pence plans to campaign heavily in Iowa, hitting all 99 counties, as his team sees a path for him to secure the GOP nomination by winning over conservative evangelical Christians in the state who have soured on Trump. Later in the week, Pence heads to New Hampshire, which holds the first-in-the-nation GOP primary.

“Evangelicals are very wide open in Iowa, and beyond Iowa, in looking for the candidate who they want to support,” Bob Vander Plaats, the influential president of The Family Leader, a conservative Iowa group, told CNN in a recent interview.

Vander Plaats, who has not yet endorsed in the primary but has known Pence personally for years, said Iowans have received the former vice president “exceptionally well” during his visits to the state ahead of his formal announcement.

In breaking with Trump, however, Pence may have alienated some of Trump’s most loyal supporters. Though other Republicans have applauded him for his actions on January 6.

“I think every candidate is going to have their hill to climb or hurdle to cross. And that probably is going to be Mike Pence’s,” Vander Plaats said, when asked if Pence’s standing among GOP voters angry over his actions on January 6 would complicate his path to the nomination.

This story and headline have been updated with additional details.

CNN’s Kyung Lah contributed to this report.