(Reuters) – BP Chief Executive Tony Hayward has come under increasing pressure since a Gulf of Mexico well blew out on April 20, killing 11 workers and starting a 60,000 barrels per day crude spill.

Green Business | Barack Obama | Gulf Oil Spill

Investors and analysts have backed his response and his stewardship of BP since he took office in 2007.

But U.S. President Barack Obama said he would have sacked Hayward, if he worked for the President, for comments that appeared to play down the damage of the spill, and for saying he wanted his life back.

The following are the candidates seen as most likely to succeed Hayward if he goes. The list is limited to internal candidates, because BP and its peers tend to hire internally. All the CEOs of the five biggest Western oil companies — Exxon Mobil, Chevron, France’s Total and Royal Dutch Shell — spent all or almost all of their careers at their current employer.

Andy Inglis – the Engineer

Inglis (pronounced Ingalls), head of BP’s core exploration and production division, might under normal circumstances be the favorite to replace Tony Hayward.

The division is responsible for the vast majority of BP’s earnings and the last two people to head it went on to become

CEO.

Inglis, 50 was considered for the top job back in 2006 when, as deputy head of E&P, he lost out to his then boss, Hayward.

However, the oil spill could play against him this time — especially if it is found that, as some lawmakers have claimed, corners were cut to expedite the drilling of the well.

Inglis is from the North of England and has an accent to match, although his many years living in the U.S. also come across in his voice.

Colleagues say Inglis has a love of the nuts and bolts of the oil business. He joined BP from the prestigious Cambridge University and, like his father before him, he has been made a fellow of both the Institute of Mechanical Engineers and of the Royal Academy of Engineering.

Inglis is married, with five children — three with his current wife, and two by his first wife, who died in 1994.

Iain Conn – the Trader

Iain Conn, the head of BP’s refining and marketing unit and another BP lifer, is seen by many as the favorite to succeed Hayward. Of all the candidates, bookie Paddy Power is offering the shortest odds on his elevation.

Although also an engineering graduate, Conn speaks more frequently about, and is better known for, his time as a trader.

He spent the first eight years of his career with BP in the oil trading department, where he pioneered the use of technical analysis.

Conn, 47, was also on the 2006 shortlist as possible successors to former CEO John Browne.

Conn has bolstered his reputation in recent years, successfully turning around BP’s troubled refining unit, improving performance at facilities and cutting costs.

He also has experience in exploration and production gleaned from roles in the United States and Colombia.

However, continued regulatory criticism of safety at BP’s U.S. refineries could play against him too, given bolstering its reputation in the U.S. will be a key focus for BP in future.

The always smartly attired Conn is married with three children and, like Hayward, he met his wife at BP, where she worked in the trading department.

He likes playing jazz and blues music on the piano and saxophone and is a passionate fisherman who travels to the West of Ireland most summers to catch salmon.

Bob Dudley – the Diplomat

Bob Dudley has the ill-defined role of “Managing Director” with responsibility for oversight of the Americas and Asia.

Hayward has described Dudley as “the management team’s Foreign Secretary — or perhaps Secretary of State in American terms.”

These diplomatic skills are currently being employed on U.S. TV networks, acting as a more palatable, U.S. face of the oil giant’s oil spill response.

Dudley has also been named to head a unit that will be responsible for managing the aftermath of the oil spill, when the leak is capped.

However, some think he has the skills to manage BP itself.

Dudley is best known for his role as head of BP’s Russian joint venture, TNK-BP, from its formation in 2003 until 2008.

Supporters say this shows he knows how to run a big oil company. Under Dudley, TNK-BP, which BP formed by merging assets with a group of billionaire oligarchs, grew oil output 33 percent to 1.6 million barrels per day.

His time there also gave him considerable experience of the political risks involved in the industry. BP fell out with its partners when they tried to exercise more control over TNK-BP. Things got ugly, and Dudley was forced to flee the country as BP accused the government of doing nothing to defend its interests.

Dudley was born in New York, which would help offset some of the anti-British sentiment that has stuck to the company many U.S. politicians insist on calling “British Petroleum,” the name the company ditched over a decade ago.

Dudley joined BP through its takeover of Amoco, which he had joined as a field engineer in Texas. He has also worked in the field in China and Scotland.

With his thinning grey hair and calm manner, Dudley seems a little older than his 54 years — a factor that may play against him in a company where executives are expected to retire at 60.

Dudley is married with two children at university. (Reporting by Tom Bergin; Editing by Andrew Callus)