BOSTON (AP) - Democratic U.S. Senate hopeful Elizabeth Warren is being joined on the campaign trail by the longest serving woman in the Senate - Maryland Democrat Barbara Mikulski.

Warren and Mikulski are scheduled to appear together at an event Friday at noon at the University of Massachusetts in Boston.

The campaign said the two will discuss what they think is at stake for Massachusetts voters on Election Day.

Warren is locked in a tight race with Republican incumbent Sen. Scott Brown. The contest is already the most expensive political battle in Massachusetts history.

Warren will also be getting a boost from Democratic Gov. Deval Patrick.

Patrick is scheduled to greet Warren volunteers and help kick off a Warren campaign phone bank in Boston's Roxbury neighborhood Friday afternoon.