The one thing Mike Pence needs to beat his old boss in 2024

In a traditional American political world, Mike Pence's 2024 presidential campaign would have a lot going for it.

A politician with experience in both Congress and as a state governor. A former vice-president who had multiple high-profile administration roles and four years to build connections with his party's grass-roots. A methodical but reasonably charismatic public speaker who has a track record of strong debate performances and a stint as a popular conservative radio host.

This is not, however, a normal political world anymore - and it hasn't been since Donald Trump barrelled his way to the Republican presidential nomination and the White House in 2016.

Instead, 2024 will be yet another precedent-setting moment in modern American politics - the first time a former vice-president and his former president will compete for their party's presidential nomination.

In a campaign video that quoted Ronald Reagan and Abraham Lincoln, Mr Pence launched his new mission on Wednesday.

"Pence is a traditional conservative," says David Oman, former chair of the Iowa Republican Party. "He's just not a loud one."

For the moment, Mr Pence's former boss has almost all the advantages. He has a massive campaign war chest, high approval ratings among Republican voters and unwavering support from roughly 30% of his party's voters.

That loyal Trump base also views Mr Pence with scepticism that veers toward animosity. They consider his decision not to back the former president's attempt to overturn their 2020 electoral defeat an error at best and, frequently, as a betrayal.

Last month, Mr Pence was compelled to testify before a federal grand jury investigating the former president's role in the January 6th attack on the US Capitol and efforts to reverse the 2020 results.

And in March, Mr Pence said that Mr Trump's "reckless words" put his family in danger on that day, adding that "history will hold Donald Trump accountable".

For the moment, however, it appears Mr Trump's supporters are the ones passing judgement on Mr Pence.

To succeed in his presidential bid, Mr Pence will need the former president to falter. But if that happens it is much more likely that his supporters go to someone like Florida Governor Ron DeSantis.

There is an area where Mr Pence has an edge over his former running mate, however.

As a devout Christian, the Indiana politician has a long history of close ties to the US evangelical community. One of the reasons Mr Trump chose him for his 2016 ticket was because his campaign advisers believed Mr Pence would assuage the concerns of Christian voters who might be reluctant to support the thrice-married New Yorker with considerable personal baggage.

Mr Pence was effectively the Trump administration's ambassador to the Christian right, touting wins on high-profile cultural issues like abortion and religious freedom.

Now he hopes to capitalise on that history and peel away the former president's evangelical voters. That's particularly important in Iowa, the state that holds the first Republican presidential nomination contest and where Christian conservatives hold considerable sway.

"It's a good bloc of 30 plus percent of the Republican voters who will show up on caucus night in early 2024," says Mr Oman. "So it's a bloc that candidates have to take seriously."

The challenge for Mr Pence is there will be other candidates also competing for the evangelical vote. They include Mr DeSantis - who has championed conservative cultural issues in Florida - and South Carolina Senator Tim Scott. The more the field is crowded and divided, the greater the chance that no one will be able to defeat Mr Trump.

"Pence starts off with a decent part of a Republican base that will not support him," Mr Oman says. "He has to talk about the kind of governor he was, be among those who talk about ideas for the future, someone who can show some common sense and give people a credible alternative to his former partner, Donald Trump."

Mr Pence has been manoeuvring for a presidential bid for more than a year - well before Mr Trump made his White House ambitions clear. And given that another former vice-president currently sits in the Oval Office, his presidential dreams are not unimaginable - even if the path he would have to take to get to the White House is without precedent.