This former advertising executive bears such a striking resemblance to US presidential hopeful Hillary Clinton that she quit her job to work as a full-time lookalike.

Clinton's 'twin', Teresa Barnwell, 61, earns thousands every month for impersonating the presumptive Democratic nominee.

She stands to earn even more if the former Secretary of State defeats business mogul Donald Trump, the presumptive nominee for the Republicans, this November and becomes president.

Teresa Barnwell earns thousands for impersonating presumptive Democratic nominee Hillary Clinton

Barnwell quit her job in advertising and has been a full-time Hillary Clinton lookalike for more than 20 years

Barnwell (left) said Clinton was 'really lovely' when they meet at a book signing in Los Angeles in 1996

Democratic presidential candidate Hillary Clinton addresses the National Education Association on July 5

Barnwell, from Palm Desert, California, was first told she looked identical to Clinton, 68, when she was playing a slot machine more than 20 years ago.

When Bill Clinton became the 42nd president in 1993, she was bombarded by people telling her she was the first lady's doppelganger.

Because they looked so much alike, she decided to quit her job in advertising 23 years ago and become a full-time Clinton impersonator.

Since Clinton announced her plans to run for president last year, Barnwell has seen bookings skyrocket and in a month she can make up to $10,000 or even more.

She's been invited all over the world for photo shoots, TV commercials, music videos and corporate events, meeting the likes of comedian Jay Leno, WikiLeaks founder Julian Assange, former Secretary of State Colin Powell and Clinton herself.

Barnwell (left) has traveled the world while impersonating Clinton (right) and has seen bookings increase

Barnwell poses with Donald Trump impersonator Marcel Forestieri during an appearance in Park City, Utah

Barnwell met Clinton at a book signing in Los Angeles in 1996, but have never bumped into each other since.

With her work taking her all over the world and at various stops on the political trail, Barnwell said she avoids Clinton if they are in the same place at the same time.

'Once it felt like she was following me, wherever I went Hillary would be heading to shortly after - it became quite tricky as I think she'd find it a little creepy seeing her doppelganger in real life,' she said. 'The only time I met her was at a book signing, I had to take my opportunity then and asked her if anyone ever told her she looked like me - which she found amusing.

'She was really lovely and even joked I could go to all the functions she didn't want to attend,' Barnwell added.

Barnwell said she has to act responsibly when performing as Clinton and turns down jobs that she feels are inappropriate or could damage the politician's reputation.

'Sometimes I get weird requests, like once I was asked to be a Hillary stripper, which I thought was pretty bad so I turned it down - I wouldn't want to damage either of our reputations,' she said. 'I don't think it would be right to portray Hillary in a particular way, I don't mind doing comedy or poking fun at her, but sometimes it can be too much.'

Barnwell (with her husband, Holton) said it's difficult to have a normal life due to her resemblance to Clinton

Hillary Clinton lookalike Teresa Barnwell poses for a photo with former Secretary of State Colin Powell

She said she has posed for photos while modeling men's underwear with smiley faces, and even gave a speech at an event in Texas where wild pigs were running around.

But it's not all fun and games for Barnwell, who said it's hard to have a normal life because she looks so similar to Clinton.

She said people on the street even confuse her for the presidential candidate and ask for selfies.

'It's not that hard for me to become Hillary because I already look like I'm her twin,' said Barnwell. 'I have such a strong, natural resemblance to Hillary that people always approach me asking for a picture or to remind me that I look like Hillary.

'I can't even get groceries without someone saying something or being shocked I'm buying something ordinary like bananas because they think I'm really her,' she said. 'Once a group of Japanese tourists at an event were so honored to meet me because they believed I was the real Hillary.

'Later we were mobbed by people wanting autographs and pictures, people were pulling on my arms, my clothes, everything, security had to help us leave.'

Barnwell was coached by Denise Bella Vlasis, a Madonna lookalike, to hone her craft after meeting on the set of a TV show.

Vlasis, 52, who owns Tribute Productions Talent, said presidential lookalikes are probably the most requested and best paid impersonators.

'Clients love to have talents that are not only talented at the impression of the star, but they all hope the lookalike talent truly looks like the person they emulate,' said Vlasis. 'I feel Teresa brings the energy, look and character of Hillary Clinton to each booking, she has this essence and energy which lookalike talents must have in order to portray a convincing performance.