Mike Pence rips Trump as he launches his 2024 GOP presidential bid

ANKENY, Iowa — Former Vice President Mike Pence kicked off his bid for the Republican presidential nomination Wednesday by accusing his two-time running mate, former President Donald Trump, of abandoning conservatism and standing against the Constitution on Jan. 6.

"When Donald Trump ran for president in 2016, he promised to govern as a conservative, and together we did just that," Pence said. "Today, he makes no such promise."

Pence cited abortion as a prominent example of Trump's drifting away from the party's conservative principles.

"The sanctity of life has been our party's calling for half a century — long before Donald Trump was ever a part of it," Pence said. "Now he treats it as an inconvenience, even blaming election losses in 2022 on overturning Roe v. Wade."

Those remarks, coupled with a rebuke of Trump's efforts to overturn the 2020 election, represent Pence's most aggressive public repudiation of Trump ever.

A president who put himself above the Constitution — and asked his vice president to do the same — “should never be president of the United States again,” Pence said.

Pence, who certified the 2020 election results under threat from supporters of Trump, reiterated Wednesday that he did not have the constitutional authority to stop the count and would have set the wrong precedent had he tried.

"President Trump also demanded that I choose between him and the Constitution," Pence said, leaning into the most evident contrast between the two men. "Now voters will be faced with the same choice. I chose the Constitution, and I always will."

He went into the wording of the Constitution to explain the powers of the vice presidency — and how expanding them could harm Republicans in the future.

"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," Pence said. "I had no right to overturn the election, and [Vice President] Kamala Harris will have no right to overturn the election when we beat them in 2024."

Pence concluded that Trump "demanded that I choose between him and the Constitution," adding, "Now voters will be faced with the same choice."

More broadly, Pence argues that Trump and President Joe Biden have not lived up to the standards of civility that he says Americans seek in their leaders.

"Most Americans treat each other with kindness and respect — even when we disagree," Pence planned to say. "It's not too much to ask our leaders to do the same. It's clear that neither Joe Biden nor Donald Trump share this belief, and neither of them intend to bring this nation together."

Earlier in the day, his 64th birthday, Pence, the former Indiana governor and six-term congressman, released a launch video taking whacks at Biden by name and Trump by implication.

"President Joe Biden and the radical left have weakened America at home and abroad," Pence said in a self-narrated 2½-minute montage of Americana. "We can turn this country around. But different times call for different leadership."

Turning more squarely toward the oft-spiteful Trump, Pence added, "Today, our party and our country need a leader that will appeal, as Lincoln said, to the better angels of our nature."

In the video, titled “Best Days,” Pence contends that the country is in bad shape but that its “best days” are ahead.

One of three candidates to enter the GOP primary field this week — former New Jersey Gov. Chris Christie jumped in Tuesday, and North Dakota Gov. Doug Burgum is expected to announce Wednesday — Pence sees Iowa's first-in-the-nation caucus as fertile ground for his brand of traditional and faith-based conservatism.

There is little question that he faces a steep uphill battle to compete for the party's nomination when Trump has a majority of GOP voters in most national polls and Florida Gov. Ron DeSantis is running a clear second with 22.4% in the RealClearPolitics average of recent surveys.

Trump allies welcomed Pence to the race as a potential drain on DeSantis' support.

“Mike Pence’s entrance into the race caps off another bad week for Ron DeSantis’ faltering campaign," Karoline Leavitt, spokeswoman for Make America Great Again Inc., a pro-Trump political committee, said in a statement. "But the question most GOP voters are asking themselves about Pence’s candidacy is ‘Why?’”

Pence is in fourth place, behind Trump, DeSantis and Nikki Haley, the former U.S. ambassador to the U.N., with less than 4% in the RealClearPolitics average.

But beyond the numbers, a Pence comeback would require an epic reversal of political dynamics within the GOP.

Less than three years ago, Pence hid as a mob spurred on by Trump ransacked the Capitol. Some in the crowd, angry over his refusal to block the certification of the 2020 defeat of the Trump-Pence ticket, chanted, "Hang Mike Pence!"

It was a dramatic turn for a loyal partisan who had spent his years in the vice presidency nodding at Trump's side. At times, Pence's support was crucial to Trump, particularly when they first ran together in 2016.

Back then, some conservatives — particularly evangelical Christians — were wary that Trump would stray from the Republican base. Others were appalled by his personal conduct, including the release of an "Access Hollywood" tape in which Trump bragged about the ease with which he could sexually assault women with impunity.

Pence, who sought to curtail abortion and gay rights in Congress and as governor of Indiana, acted as an important validator for Trump.

Now, like the other Republicans in the race, he faces the immense challenge of cutting into Trump's support and consolidating the universe of GOP voters who bear antipathy toward Trump or are simply open to another candidate.

And while Pence has near-universal name recognition among voters, an asset for most candidates, his low poll numbers suggest his challenge is complicated by the fact that the electorate's views of him has already been formed.

"Mike Pence is a true conservative and a great public servant," said Dan Eberhart, a GOP donor who backs DeSantis. "He just doesn't have the support among Republicans that he needs to be competitive."

Pence campaign officials are well aware that they have to recast the public narrative about him. They hope they can reintroduce him not as Trump's vice president or as the man who stood between the mob and the Constitution but as the conservative leader he was in Congress and in Indiana.

Pence, an advocate for President George W. Bush's wars in Afghanistan and Iraq, has been steadfast in his support for U.S. aid to Ukraine when Trump and DeSantis have questioned the wisdom of that mission.

He has also distinguished himself from the front-runners by calling for cuts to Social Security and Medicare, a policy position that is popular with economic conservatives but anathema to more populist Republicans.

He reiterated that distinction in Wednesday's remarks, chiding fellow Republican candidates for inattention to mounting debt.

As a member of the House, Pence stood against Bush as a leader of a rebel group that opposed his enactment of a prescription drug program for Medicare. He was also a leading advocate for dead-on-arrival conservative-faction budgets that would have slashed entitlement programs.

On abortion, an issue that has fractured the GOP since the Supreme Court overturned federal protection for the procedure last year, Pence has called for a national ban. Trump, who appointed three of the justices who voted in the majority, has stopped short of that. DeSantis, who recently signed a six-week ban into law in Florida, has avoided the question of whether he would sign a measure outlawing abortion across the nation.

Pence's throwback Republican platform — strong national defense, reductions in spending and conservative social policy — has allowed allies to see a glimmer of hope in Iowa, which is why he is launching his campaign there.

“We view this race as absolutely wide open, and Iowa is really going to solidify itself as the pivotal player,” a person familiar with Pence’s plans said last week. “It’s a place that values Mike Pence’s principles — traditional conservative principles — deep-rooted faith and uncommon character.”

This article was originally published on NBCNews.com