DES MOINES, Iowa (AP) — Former Vice President Mike Pence promised "the best days of the greatest nation on earth are yet to come" in a video released Wednesday formally launching his campaign for the Republican nomination for president.

"Different times call for different leadership," Pence, who served four years alongside then-President Donald Trump, says in the video, released via Fox News and Twitter hours ahead of a kickoff event in Des Moines. "Today our party and our country need a leader that'll appeal, as Lincoln said, to the better angels of our nature."

While it would be "easy to stay on the sidelines," he adds, "that's not how I was raised. That's why today, before God and my family, I'm announcing I'm running for president of the United States."

With Pence's entry into the race, the GOP field is largely set. It includes Trump, who's leading in early polls, Florida Gov. Ron DeSantis, who remains in second, former United Nations Ambassador Nikki Haley, South Carolina Sen. Tim Scott, former New Jersey Gov. Chris Christie, former Arkansas Gov. Asa Hutchinson and North Dakota Gov. Doug Burgum, who also was launching his campaign Wednesday.

Pence is staking his presidential hopes on Iowa as he launches a campaign that will make him the first vice president in modern history to take on his former running mate.

Pence's campaign will also test the party's appetite for a socially conservative, mild-mannered and deeply religious candidate who has denounced the populist tide that has swept through his party under Trump. And it will show whether Pence still has a political future after Jan. 6, 2021, when a large portion of GOP voters still believe Trump's lies that the 2020 election was stolen and that Pence had the power to reject the results of the election, won by Democrat Joe Biden.

Pence and his advisers see Iowa — the state that will cast the first votes of the GOP nominating calendar — as key to his potential pathway to the nomination. Its caucus-goers include a large portion of evangelical Christian voters, whom they see as a natural constituency for Pence, a social conservative who supports a national ban on abortion and often talks about his faith. They also think Pence, who represented Indiana in Congress and as governor, is a good personality fit with the Midwestern state.

"We believe the path to victory runs through Iowa and all of its 99 counties," said Scott Reed, co-chair of a super PAC that launched last month to support Pence's candidacy.

Iowa has typically been seen as a launching pad for presidential candidates, delivering momentum, money and attention to hopefuls who win or defy expectations. But recent past winners including Ted Cruz, Rick Santorum and Mike Huckabee have failed to ultimately win the nomination.

And Pence faces steep challenges. He enters the race as among the best-known Republican candidates in the crowded GOP field. But Pence — seen by Trump critics as complicit with his most indefensible actions and maligned by Trump loyalists as a traitor — is also saddled with high unfavorable ratings.

A CNN poll conducted last month found 45% of Republicans and Republican-leaning independents said they would not support Pence under any circumstance. Only 16% said the same about Trump.

Pence's favorability has also slipped in Iowa, according to The Des Moines Register/Mediacom Iowa Poll.

Shortly after leaving office, in June 2021, 86% of Iowa Republicans said they had a favorable view of Pence. But the Register's March Iowa Poll showed that figure had dropped to 66%. The poll also found Pence with higher unfavorable ratings than all of the other candidates it asked about, including Trump and DeSantis, with 26% of Republicans polled saying they have a "somewhat" or "very" unfavorable view of him.

And just 58% of Iowa evangelicals said they had favorable feelings toward Pence — a particularly disappointing number, given his campaign's strategy.

But Pence, who has already visited Iowa more than a dozen times since leaving office, has also received a warm welcome from voters during his trips. During a "Roast and Ride" event over the weekend that drew a long list of 2024 candidates, Pence stood out as the only candidate to actually mount a Harley and participate in the event's annual motorcycle ride. When he arrived at a barbecue at the state fairgrounds, he moved easily from table to table, warmly greeting and chatting with attendees.

But there remains lingering skepticism of Pence among many Republican voters who adhere to the baseless but persistent conspiracy theory that the 2020 election was stolen. Many who cling to the falsehood believe Pence was complicit in the plot to deny Trump a second term because he refused Trump's pressure campaign to reject the Electoral College vote when he presided over a joint session of Congress on Jan. 6, 2021, when a mob of Trump's supporters violently stormed the building, with some chanting "Hang Mike Pence!" Pence had no such authority in his ceremonial role.

Pence advisers say they recognize the challenge and intend to explain to voters directly that Pence was adhering to his constitutional duty and never had the power to impact the vote.

"I think it's something you have to walk straight through," said his longtime adviser Marc Short.

Beyond Jan. 6, his team sees their primary goal as reintroducing Pence to a country that largely knows him as Trump's second-in-command. They want to remind voters of his time in congressional leadership and as governor and are planning a campaign heavy with town halls, house parties and visits to local diners and Pizza Ranch restaurants —- more intimate settings that will help voters get to know him personally.

"People have seen Mike Pence the vice president. I think what people are going to see is Mike Pence the person," said Todd Hudson, the speaker of the House in Indiana and a longtime Pence friend who has signed on to help with outreach to state legislators. "I'm super excited for people to get to know the Mike Pence that I know, who's funny, who's just a wonderful person... the more relaxed Mike Pence."

Reed believes there is a strong desire in the party for a candidate like Pence who espouses Reagan-style conservatism, including traditional social values, hawkish foreign policy and small government economics.

"We think this nomination fight is going to be an epic battle for the heart and soul of the conservative, traditional wing of the Republican Party. And Pence is going to campaign as a classic conservative. His credentials are unmatched," he said.

Unlike Trump and DeSantis, Pence has argued that cuts to Social Security and Medicare must be on the table and has blasted those who have questioned why the U.S. should continue to send aid to Ukraine to counter Russian aggression.

"We are not going to try to out-Trump Pence. Everybody else is," Reed said. "Pence is the only candidate running not to be Trump's VP."