WASHINGTON (NewsNation) — Former Vice President Mike Pence launched his presidential campaign on Wednesday, joining a crowded 2024 Republican primary field where his former boss is the leading contender.

“This country has been so good to my family and I’ve been honored to serve it,” Pence said in his speech in Iowa. “It would be easy to stay on the sidelines. That’s not how I was raised. I’ve long believed that to whom much is given, much will be required. That’s why today before God and my family, I’m announcing that I’m running for president of the United States of America.”

In an announcement video posted on Twitter, Pence hits at President Joe Biden, blaming his administration for high inflation, the situation at the border and unstable international security.

The former vice president also takes a subtle swipe at former president Donald Trump in the video, stating that “different times call for different leadership.”

Since leaving the White House, Pence has notably been critical of Trump’s effort to overturn the results of the 2020 election. He has said Trump put his vice president’s life in danger by encouraging a mob of violent protesters to storm the Capitol on Jan. 6, 2021, in an effort to stop the certification of Electoral College votes.

“Jan. 6 was a tragic day in the life of our nation. But thanks to the courage of law enforcement, the violence was quelled, and we reconvened the Congress the very same day, to complete the work of the American people under the Constitution of the United States,” Pence said. “On that fateful day, President Trump’s words were reckless. They endangered my family and everyone at the Capitol.”

Now, the former ticketmates will challenge each other in a primary that will test the staying power of Trump, who many in the party argue is unelectable in a general election.

On Wednesday, Pence frequently lauded the accomplishments of the “Trump-Pence administration,” but said the two had different visions for the future of the Republican Party and even the country itself.

On Jan. 6, Pence said, Trump asked him to choose between him and the Constitution.

“I chose the Constitution and I always will,” Pence said. “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.”

Pence’s team sees Iowa and its evangelical Christian voters as critical to his potential path to victory. Advisers say he plans to campaign aggressively in the state, hitting every one of its 99 counties before its first-in-the-nation caucuses next year.

The campaign is expected to lean heavily on town halls and retail stops aimed at reintroducing Pence to voters who only know him from his time as Trump’s second-in-command. Pence served for more than a decade in Congress and as Indiana’s governor before he was tapped as Trump’s running mate in 2016.

Pence joins a Republican field that includes Trump, Florida Gov. Ron DeSantis, former United Nations Ambassador Nikki Haley and Sen. Tim Scott, among others. Pence is polling at just over 5%, according to a FiveThirtyEight average, behind Trump and DeSantis.

Pence’s former chief of staff, Marc Short, shrugged off the poll numbers last month, saying they don’t mean much this early in the race.

“There’s a long road ahead here,” Short said at the time. “I think it’s important for Americans to actually see these candidates on a debate stage and … in a conversation with each other.”

Only six former U.S. vice presidents have been elected to the White House, including Biden, who is running for a second term.

A staunch opponent of abortion rights, Pence supports a national ban on the procedure and has campaigned against transgender-affirming policies in schools.

He has also argued that changes to Social Security and Medicare, like raising the age for qualification, should be on the table to keep the programs solvent — which both Trump and DeSantis have opposed — and criticized DeSantis for his escalating feud with Disney.

Pence has said the U.S. should offer more support to Ukraine against Russian aggression, while admonishing “Putin apologists” in the party unwilling to stand up to the Russian leader.

The Associated Press contributed to this report.