Washington, D.C. ? Valerie Jarrett, a prominent Chicago business and political figure and influential member of President-elect Barack Obama’s inner circle, is poised to play a crucial role in the White House as a public liaison and senior aide to the president.

In an official announcement due today, Jarrett will be named senior adviser and assistant to the president in charge of intergovernmental relations.

The job means she will have the ear of the president and act as a go-between with state and local elected officials and public interest groups, according to a source close to Obama advisers.

The appointment is one of the key early assignments of the Obama administration, and comes on the heels of speculation that Jarrett might be appointed to take Obama’s place in the U.S. Senate or possibly serve as head of a federal agency.

But as a trusted Obama family friend and confidante to the president-elect, Jarrett is seen by many Democrats as more valuable closer in, as a top aide in the White House. The appointment means the longtime Chicagoan will move to Washington, D.C., to assume a key role in the administration as it takes shape.