Barack Obama, the US president, visited residents of the Gulf of Mexico coast on Friday, telling them that they will not be abandoned, although he cautioned there was no "silver bullet" solution to the biggest oil spill in US history.
Obama also pledged to triple the manpower deployed to assist the cleanup, saying the government would do "whatever it takes" to aid those affected by the spill.
So far more than 20,000 people have joined the effort to contain the spill and clear the oil washing up along the Gulf coast.
"You will not be abandoned. You will not be left behind. We are on your side and we will see this through," Obama said in a statement after his second visit to the region.
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"I am the president and the buck stops with me," he said.
Obama was speaking in Louisiana after meeting local and state officials and inspecting the oil spill damage to the region's coastline as he sought to defend his administration's response to the disaster.
The spill has inundated large areas of the state's fragile coastal marshlands and closed down the lucrative fishing trade.
Frustrated Gulf coast residents have criticised US federal authorities for being slow to act and offering too little assistance.
The White House vigorously disputes such claims, insisting it has mounted the largest response in history.
Following his visit Obama also again pledged to make British oil giant BP pay for all damages caused by the huge slick.
"We're going to keep at this every day until the leak is stopped, until this coastline is clean, and your communities are made whole again," he said.
"That's my promise to you. And that is a promise on behalf of a nation. It is one that we will keep."
BP began its latest effort to plug the well on Wednesday afternoon and then stopped pumping mud overnight to analyse pressure readings.
However, BP said that the success of the clean-up operation, never attempted at such depths, was still uncertain.
"We have wrestled it to the ground but we haven't put a bullet in its head yet," Hayward said while aboard a helicopter over the spill site.
|Anger is growing over BP's response to the Gulf of Mexico spill [AFP]
He said the top kill's chance of success were about 60 to 70 per cent.
The company did not publicise the halt for many hours, drawing fresh accusations it was concealing information from the public - charges which the company has denied.
If the top kill method fails, BP has said it will try other possible solutions, including a second attempt at containing the oil so it can be transported by pipe to a ship at the water's surface or placing a new blowout preventer atop the failed one.
In his statement on Friday Obama warned that even if BP succeeds in risky "top kill" operation, the government will be left with a massive job to clean up the millions of litres of oil spilled from the well.
"There are not going to be silver bullets or a lot of perfect answers for some of the challenges that we face," he said.
"This is a man-made catastrophe that is still evolving."