President Obama on Thursday authorized the Pentagon to call up reserve and National Guard troops if they are needed to assist in the U.S. response to the Ebola outbreak in West Africa. 

Obama signed an executive order that allows the government to call up more forces and for longer periods of time than currently authorized. There is no actual call-up at this point. 

The U.S. has committed to send up to 4,000 military personnel to West Africa to provide logistics and humanitarian assistance and help build treatment units to confront the rapidly spreading and deadly virus. 

Obama also notified top congressional officials of his move. 

Nearly 4,500 people have died from the Ebola outbreak, most of them in Liberia, Sierra Leone and Guinea. The White House has said the troops will not be providing direct health care aid. 

Separately, Obama placed phone calls to House Speaker John Boehner, House Democratic leader Nancy Pelosi and Senate Majority Leader Harry Reid to discuss the administration's response to the disease. 

He also was consulting with administration public health officials and heads of state about the Ebola outbreak. 

Obama canceled a Thursday campaign trip to stay at the White House and focus on Ebola. It's the second day in a row he nixed a planned trip because of the outbreak. 

Obama was to meet late Thursday afternoon with administration and White House officials who are working on the government response to the West Africa outbreak and on health security measures in the U.S. 

White House spokesman Josh Earnest said Obama will also hold a conference call with health care workers from the Centers for Disease Control and Prevention.