The phrase "assume direct responsibility" is correct and usable in written English.
You can use it when indicating that someone is taking on a specific duty or obligation, particularly in a professional or formal context.
Example: "As the project manager, I will assume direct responsibility for ensuring that all deadlines are met."
Alternatives: "take full responsibility" or "accept direct accountability".
President Bush himself, backed by Tom Ridge, his homeland security director, must assume direct responsibility for this wartime effort.
Now, the state is moving to assume direct responsibility for maintenance of its court buildings in Nassau.
The new president said he would assume direct responsibility for creating more opportunities for indigenous people to take part in government activities, and for guaranteeing their political rights.
Peter Stringham, 49, chairman and chief executive of Y. & R. Advertising North America to whom the New York office reports, will assume direct responsibility for that operation.
But as he engages Congress on the issue, Mr. Bush needs to take another step and press for creation of a federal transportation police force to assume direct responsibility for all airport security functions.
On Monday April 4th, Rick Wagoner, the firm's chairman and chief executive, said that he would assume direct responsibility for GM's North American operations in an attempt to reverse the company's decline.
Mendelson said the issues arose after the police department assumed direct responsibility for the operations of the cameras.
He assumed direct responsibility for the F.B.I.'s investigation of the Khobar Towers bombing in Dhahran, Saudi Arabia, in July 1996, which killed 19 American airmen.
He said that he now considered many of these grants to be excessive and that he had assumed direct responsibility for voting on stock option plans.
However, because of Greater London's special status as national capital, the central government of the United Kingdom assumed direct responsibility for other functions usually performed by local governments.
She added that Mr. Obama had assumed "direct responsibility" for investigating the spying allegations, agreeing to give the Brazilian government information on the surveillance practices by Wednesday.
