The activists camped out at the Denver office Thursday are part of a five-person group of illegal immigrant students walking across the country to demand the president sign an executive order enacting the DREAM Act.
They said they began the strike Tuesday evening. Campaign staffers are using a back door in an alley to get into the office.
The DREAM Act would allow the children of illegal immigrants to enroll in college or the military and eventually establish citizenship or permanent residency in the U.S.
The Obama campaign says it supports the cause but that the only permanent solution is to have Congress pass the DREAM Act.