President Barack Obama is raising millions of dollars for his re-election bid, spending three days on the West Coast to stock up for the long campaign ahead.

Obama was holding four fundraisers on Thursday in the Los Angeles area and in San Francisco, courting reliable Democratic donors at a time when the Republican presidential contest remains unsettled.

Obama was expected to raise more than $8 million with events that will take him from California to the Seattle area on Friday.

The president is urging Democrats to mobilize - telling supporters in Los Angeles that the campaign is "not going to be easier this time."

He says "people out there are hurting and they need us to do more."