  The strong dependence of the neutrino annihilation mechanism on the mass
accretion rate makes it difficult to explain the LGRBs with duration in excess
of 100 seconds as well as the precursors separated from the main gamma-ray
pulse by few hundreds of seconds. Even more difficult is to explain the Swift
observations of the shallow decay phase and X-ray flares, if they indeed
indicate activity of the central engine for as long as 10,000 seconds. These
data suggest that some other, most likely magnetic mechanisms have to be
considered. The magnetic models do not require the development of accretion
disk within the first few seconds of the stellar collapse and hence do not
require very rapidly rotating stellar cores at the pre-supernova state. This
widens the range of potential LGRB progenitors. In this paper, we re-examine
the close binary scenario allowing for the possibility of late development of
accretion disks in the collapsar model and investigate the available range of
mass accretion rates, black hole masses, and spins. A particularly interesting
version of the binary progenitor involves merger of a WR star with an
ultra-compact companion, neutron star or black hole. In this case we expect the
formation of very long-lived accretion disks, that may explain the phase of
shallow decay and X-ray flares observed by Swift. Similarly long-lived magnetic
central engines are expected in the current single star models of LGRB
progenitors due to their assumed exceptionally fast rotation.
