Former president Jimmy Carter carved an unlikely path to the White House in 1976 and endured humbling defeat after one term. Now, six administrations later, the longest-living chief executive in American history is re-emerging from political obscurity at the age of 94 to win over his fellow Democrats once again.

A peanut farmer turned politician then worldwide humanitarian, Mr Carter is carving out a unique role as several Democratic candidates look to his family-run campaign after the Watergate scandal as the roadmap for toppling Donald Trump in 2020.

"Jimmy Carter is a decent, well-meaning person, someone who people are talking about again given the time that we are in," Minnesota senator Amy Klobuchar said in an interview.

"He won because he worked so hard, and he had a message of truth and honesty. I think about him all the time."

Ms Klobuchar is one of at least three presidential hopefuls who have ventured to the tiny town of Plains, Georgia, to meet with Mr Carter and his wife, Rosalynn, who is 91.

The Democrat challengers to Trump in 2020 Show all 25 1 /25 The Democrat challengers to Trump in 2020 The Democrat challengers to Trump in 2020 Bernie Sanders The Vermont senator has launched a second bid for president after losing out to Hilary Clinton in the 2016 Democratic primaries. He is running on a similar platform of democratic socialist reform Getty The Democrat challengers to Trump in 2020 Joe Biden The former vice president recently faced scrutiny for inappropriate touching of women, but was thought to deal with the criticism well and has since maintained a front runner status in national polling EPA The Democrat challengers to Trump in 2020 Elizabeth Warren The Massachusetts senator is a progressive Democrat, and a major supporter of regulating Wall Street Reuters The Democrat challengers to Trump in 2020 Amy Klobuchar Klobuchar is a Minnesota senator who earned praise for her contribution to the Brett Kavanaugh hearings Getty The Democrat challengers to Trump in 2020 Michael Bloomberg Michael Bloomberg, a late addition to the 2020 race, announced his candidacy after months of speculation in November. He has launched a massive ad-buying campaign and issued an apology for the controversial "stop and frisk" programme that adversely impacted minority communities in New York City when he was mayor Getty Images The Democrat challengers to Trump in 2020 Tulsi Gabbard The Hawaii congresswoman announced her candidacy in January, but has faced tough questions on her past comments on LGBT+ rights and her stance on Syrian President Bashar al-Assad Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Pete Buttigieg The centrist Indiana mayor and war veteran would be the first openly LGBT+ president in American history Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Deval Patrick The former Massachusetts governor launched a late 2020 candidacy and received very little reception. With just a few short months until the first voters flock to the polls, the former governor is running as a centrist and believes he can unite the party's various voting blocs AFP/Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Beto O'Rourke The former Texas congressman formally launched his bid for the presidency in March. He ran on a progressive platform, stating that the US is driven by "gross differences in opportunity and outcome" AP The Democrat challengers to Trump in 2020 DROPPED OUT: Kamala Harris The former California attorney general was introduced to the national stage during Jeff Sessions’ testimony. She has endorsed Medicare-for-all and proposed a major tax-credit for the middle class AFP/Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Bill De Blasio The New York mayor announced his bid on 16 May 2019. He emerged in 2013 as a leading voice in the left wing of his party but struggled to build a national profile and has suffered a number of political setbacks in his time as mayor AFP/Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Steve Bullock The Montana governor announced his bid on 14 May. He stated "We need to defeat Donald Trump in 2020 and defeat the corrupt system that lets campaign money drown out the people's voice, so we can finally make good on the promise of a fair shot for everyone." He also highlighted the fact that he won the governor's seat in a red [Republican] state Reuters The Democrat challengers to Trump in 2020 DROPPED OUT: Cory Booker The New Jersey Senator has focused on restoring kindness and civility in American politics throughout his campaign, though he has failed to secure the same level of support and fundraising as several other senators running for the White House in 2020 Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Wayne Messam Mayor of the city of Miramar in the Miami metropolitan area, Wayne Messam said he intended to run on a progressive platform against the "broken" federal government. He favours gun regulations and was a signatory to a letter from some 400 mayors condemning President Trump's withdrawal from the Paris Climate Accord Vice News The Democrat challengers to Trump in 2020 DROPPED OUT: Kirsten Gillibrand The New York Senator formally announced her presidential bid in January, saying that “healthcare should be a right, not a privilege” Getty The Democrat challengers to Trump in 2020 DROPPED OUT: John Delaney The Maryland congressman was the first to launch his bid for presidency, making the announcement in 2017 AP The Democrat challengers to Trump in 2020 DROPPED OUT: Andrew Yang The entrepreneur announced his presidential candidacy by pledging that he would introduce a universal basic income of $1,000 a month to every American over the age of 18 Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Julian Castro The former San Antonio mayor announced his candidacy in January and said that his running has a “special meaning” for the Latino community in the US Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Marianne Williamson The author and spiritual adviser has announced her intention to run for president. She had previously run for congress as an independent in 2014 but was unsuccessful Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Eric Swalwell One of the younger candidates, Swalwell has served on multiple committees in the House of Representatives. He intended to make gun control central to his campaign but dropped out after his team said it was clear there was no path to victory Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Seth Moulton A Massachusetts congressman, Moulton is a former US soldier who is best known for trying to stop Nancy Pelosi from becoming speaker of the house. He dropped out of the race after not polling well in key states Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Jay Inslee Inslee has been governor of Washington since 2013. His bid was centred around climate change AFP/Getty The Democrat challengers to Trump in 2020 DROPPED OUT: John Hickenlooper The former governor of Colorado aimed to sell himself as an effective leader who was open to compromise, but failed to make a splash on the national stage Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Tim Ryan Ohio representative Tim Ryan ran on a campaign that hinged on his working class roots, though his messaging did not appear to resonate with voters Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Tom Steyer Democratic presidential hopeful billionaire and philanthropist Tom Steyer is a longtime Democratic donor AFP/Getty

New Jersey senator Cory Booker and Mayor Pete Buttigieg of South Bend, Indiana, have also visited with the Carters, including attending the former president's Sunday School lesson in Plains.

Mr Carter had planned to teach at Maranatha Baptist Church again on Sunday, but he was still recuperating at home days after being discharged from a Georgia hospital.

The former president had hip replacement surgery at the hospital following a fall as he was preparing for a turkey hunt.

"An extraordinary person," Mr Buttigieg told reporters after meeting Mr Carter. "A guiding light and inspiration," Mr Booker said in a statement.

Ms Klobuchar has attended Mr Carter's church lesson, as well, and said she emails with him occasionally. "He signs them 'JC,'” she said with a laugh.

The attention is quite a turnabout for a man who largely receded from party politics after his presidency, often without being missed by his party's leaders in Washington, where he was an outsider even as a White House resident.

However, more 2020 candidates have quietly sought counsel from Mr Trump's predecessor, former president Barack Obama. Several have talked with former president Bill Clinton, who left office in 2001.

But those huddles have been more hush-hush, disclosed through aides dishing anonymously. Sessions with Mr Carter, on the other hand, are trumpeted on social media and discussed freely, suggesting an appeal that Mr Obama and Mr Clinton may not have.

Unlike Mr Clinton, who was impeached after an affair with a White House intern, Mr Carter has no MeToo demerits; he and Rosalynn, married since the end of World War II, did not even like to dance with other people at state dinners. And unlike Mr Obama, who was popular among Democrats but polarising for conservatives and GOP-leaning independents, Mr Carter is difficult to define by current political fault lines.

He is an outspoken evangelical Christian who criticises Mr Trump's serial falsehoods, yet praises him for attempting a relationship with North Korean leader Kim Jong-un. Mr Carter touts his own personal relationship with Russian president Vladimir Putin, another Trump favourite. "I have his email address," Mr Carter said last September.

For years, Mr Carter has irked the foreign policy establishment with forthright criticism of Israel and its treatment of Palestinians.

He also confirmed that he voted for Vermont senator Bernie Sanders, a democratic socialist, over Hillary Clinton in Georgia's 2016 presidential primary.

In 2017, Mr Carter welcomed Mr Sanders, who is running again this year, to the Carter Centre for a programme in which the two men lambasted money in politics. Mr Carter called the United States "an oligarchy."

Yet he has since warned Democrats against "too liberal a programme," lest they ensure Mr Trump's re-election.

president Jimmy Carter says Jesus would approve of same sex marriage

Ms Klobuchar credited Mr Carter with being "ahead of his time" on several issues, including the environment and climate change (he put solar panels on the White House), health care (a major step towards universal coverage failed mostly because party liberals thought it did not go far enough) and government streamlining (an effort that angered some Democrats at the time).

But she also alluded to how his presidency ended: a landslide loss after gas lines, inflation-then-unemployment, and a 14-month-long hostage crisis in Iran. "Their administration was not perfect," she said.

It is enough of an enigma that Mr Carter is the only living president not to draw Mr Trump's ire or mockery, even if Republicans have lambasted him for decades as a liberal incompetent.

Mr Trump and Mr Carter chatted by phone earlier this spring after he sent Mr Trump a letter on China and trade. Both men said they had an amiable conversation.

Nonetheless, 2020 candidates cite Mr Carter's juxtaposition with Mr Trump.

"There was a feeling that people had been betrayed in our democracy by someone who wasn't telling the truth," Ms Klobuchar said, referring to Richard Nixon's resignation in 1974.

Mr Buttigieg said he and Mr Carter "talked about being viewed as coming out of nowhere" and how Mr Carter ran two general election campaigns entirely on the public financing system that now sits unused as candidates collectively raise money into the billions.

Ms Klobuchar recalled Mr Carter telling her that "family members would disperse to different states and then they would all come back on Friday, go back through the questions they had gotten." Then "he would talk about how he would answer them" so they would all be prepared on their next trips, she said.

It was "a different era," she added, recalling that Mr Carter said he felt "hi-tech because they had a fax machine on his plane."

Indeed, Ms Klobuchar, born in 1960, was not old enough to vote for Mr Carter until he sought a second term. Mr Booker, 50, recalls voting for Mr Carter, but in a grade-school mock election. Mr Buttigieg, 37, was not even born when he left office.

Nonetheless, Ms Klobuchar said she regularly meets Iowans who remember Mr Carter and his family members campaigning in 1975 before his rivals and national media recognised his strength, and she said she sometimes references on the campaign trail how her fellow Minnesotan and Mr Carter's vice president, Walter Mondale, remembers their term: "We obeyed the law. We told the truth. We kept the peace."

Whatever the reasons for the renewed attention, Mr Carter’s allies say they hope the 2020 campaign plays a part in bolstering his reputation as a president.

"People are tired of hearing that he was a better ex-president than president," said DuBose Porter, a former Georgia Democratic chairman who has known the Carters for decades. "Of course he's done amazing things at the Carter Centre, but he did great things for the country, and we're proud of it."